{"id":29195,"date":"2018-07-18T06:07:18","date_gmt":"2018-07-18T06:07:18","guid":{"rendered":"https:\/\/cbselibrary.com\/?p=29195"},"modified":"2020-12-02T11:46:33","modified_gmt":"2020-12-02T06:16:33","slug":"rs-aggarwal-solutions-class-10-chapter-3-linear-equations-in-two-variables","status":"publish","type":"post","link":"https:\/\/cbselibrary.com\/rs-aggarwal-solutions-class-10-chapter-3-linear-equations-in-two-variables\/","title":{"rendered":"RS Aggarwal Solutions Class 10 Chapter 3 Linear equations in two variables"},"content":{"rendered":"
These Solutions are part of RS Aggarwal Solutions Class 10<\/a>. Here we have given RS Aggarwal Solutions Class 10 Chapter 3 Linear equations in two variables<\/p>\n Question 1:<\/strong><\/span> Read More:<\/strong><\/p>\n Question 2:<\/strong><\/span> More Resources<\/strong><\/p>\n Question 3:<\/strong><\/span> Question 1:<\/strong><\/span> Question 1:<\/strong><\/span> Question 1:<\/strong><\/span> Question 1:<\/strong><\/span>Exercise 3A<\/span><\/strong><\/h3>\n
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\nQuestion 4:<\/strong><\/span>
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\nQuestion 5:<\/strong><\/span>
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\nQuestion 6:<\/strong><\/span>
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\nQuestion 7:<\/strong><\/span>
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\nQuestion 8:<\/strong><\/span>
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\nQuestion 9:<\/strong><\/span>
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\nQuestion 10:<\/strong><\/span>
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\nQuestion 11:<\/strong><\/span>
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\nQuestion 12:<\/strong><\/span>
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\nQuestion 13:<\/strong><\/span>
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\nQuestion 14:<\/strong><\/span>
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\nQuestion 15:<\/strong><\/span>
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\nQuestion 16:<\/strong><\/span>
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\nQuestion 17:<\/strong><\/span>
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\nQuestion 18:<\/strong><\/span>
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\nQuestion 19:<\/strong><\/span>
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\nQuestion 20:<\/strong><\/span>
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\nQuestion 21:<\/strong><\/span>
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\nQuestion 22:<\/strong><\/span>
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\nQuestion 23:<\/strong><\/span>
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\nQuestion 24:<\/strong><\/span>
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\nQuestion 25:<\/strong><\/span>
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\nQuestion 26:<\/strong><\/span>
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\nQuestion 27:<\/strong><\/span>
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\nQuestion 28:<\/strong><\/span>
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\n<\/p>\nExercise 3B<\/span><\/strong><\/h3>\n
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\nQuestion 2:<\/strong><\/span>
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\nQuestion 3:<\/strong><\/span>
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\nQuestion 4:<\/strong><\/span>
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\nQuestion 5:<\/strong><\/span>
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\nQuestion 6:<\/strong><\/span>
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\nQuestion 7:<\/strong><\/span>
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\nQuestion 8:<\/strong><\/span>
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\nQuestion 9:<\/strong><\/span>
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\nQuestion 10:<\/strong><\/span>
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\nQuestion 11:<\/strong><\/span>
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\nQuestion 12:<\/strong><\/span>
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\nQuestion 13:<\/strong><\/span>
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\nQuestion 14:<\/strong><\/span>
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\nQuestion 15:<\/strong><\/span>
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\nQuestion 16:<\/strong><\/span>
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\nQuestion 17:<\/strong><\/span>
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\nQuestion 18:<\/strong><\/span>
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\nQuestion 19:<\/strong><\/span>
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\nQuestion 20:<\/strong><\/span>
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\nQuestion 21:<\/strong><\/span>
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\nQuestion 22:<\/strong><\/span>
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\nTaking L.C.M, we get
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\nMultiplying (1) by 1 and (2) by
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\nSubtracting (4) from (3), we get
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\nSubstituting x = ab in (3), we get
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\nTherefore solution is x = ab, y = ab
\nQuestion 23:<\/strong><\/span>
\n6(ax + by) = 3a + 2b
\n6ax + 6by = 3a + 2b —(1)
\n6(bx – ay) = 3b – 2a
\n6bx – 6ay = 3b- 2a —(2)
\n6ax + 6by = 3a + 2b —(1)
\n6bx – 6ay = 3b – 2a —(2)
\nMultiplying (1) by a and (2) by b
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\nAdding (3) and (4), we get
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\nSubstituting in (1), we get
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\nHence, the solution is
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\nQuestion 24:<\/strong><\/span>
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\nQuestion 25:<\/strong><\/span>
\nThe given equations are
\n71x + 37y = 253 —(1)
\n37x + 71y = 287 —(2)
\nAdding (1) and (2)
\n108x + 108y = 540
\n108(x + y) = 540
\n—-(3)
\nSubtracting (2) from (1)
\n34x – 34y = 253 – 287 = -34
\n34(x – y) = -34
\n—(4)
\nAdding (3) and (4)
\n2x = 5 – 1= 4
\n\u21d2 x = 2
\nSubtracting (4) from (3)
\n2y = 5 + 1 = 6
\n\u21d2 y = 3
\nHence solution is x = 2, y = 3
\nQuestion 26:<\/strong><\/span>
\n37x + 43y = 123 —-(1)
\n43x + 37y = 117 —-(2)
\nAdding (1) and (2)
\n80x + 80y = 240
\n80(x + y) = 240
\nx + y = —-(3)
\nSubtracting (1) from (2),
\n6x – 6y = -6
\n6(x – y) = -6
\n—-(4)
\nAdding (3) and (4)
\n2x = 3 – 1 = 2
\n\u21d2 x = 1
\nSubtracting (4) from (3),
\n2y = 3 + 1 = 4
\n\u21d2 y = 2
\nHence solution is x = 1, y = 2
\nQuestion 27:<\/strong><\/span>
\n217x + 131y = 913 —(1)
\n131x + 217y = 827 —(2)
\nAdding (1) and (2), we get
\n348x + 348y = 1740
\n348(x + y) = 1740
\nx + y = 5 —-(3)
\nSubtracting (2) from (1), we get
\n86x – 86y = 86
\n86(x – y) = 86
\nx – y = 1 —(4)
\nAdding (3) and (4), we get
\n2x = 6
\nx = 3
\nputting x = 3 in (3), we get
\n3 + y = 5
\ny = 5 – 3 = 2
\nHence solution is x = 3, y = 2
\nQuestion 28:<\/strong><\/span>
\n41x – 17y = 99 —(1)
\n17x – 41y = 75 —(2)
\nAdding (1) and (2), we get
\n58x – 58y = 174
\n58(x – y) = 174
\nx – y = 3 —(3)
\nsubtracting (2) from (1), we get
\n24x + 24y = 24
\n24(x + y) = 24
\nx + y = 1 —(4)
\nAdding (3) and (4), we get
\n2x = 4 x = 2
\nPutting x = 2 in (3), we get
\n2 – y = 3
\n-y = 3 – 2 y = -1
\nHence solution is x =2, y = -1<\/p>\nExercise 3C<\/span><\/strong><\/h3>\n
\nx + 2y + 1 = 0 —(1)
\n2x – 3y – 12 = 0 —(2)
\nBy cross multiplication, we have
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\nHence, x = 3 and y = -2 is the solution
\nQuestion 2:<\/strong><\/span>
\n2x + 5y – 1 = 0 —(1)
\n2x + 3y – 3 = 0 —(2)
\nBy cross multiplication we have
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\nHence the solution is x = 3, y = -1
\nQuestion 3:<\/strong><\/span>
\n3x – 2y + 3 = 0
\n4x + 3y – 47 = 0
\nBy cross multiplication we have
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\nHence the solution is x = 5, y = 9
\nQuestion 4:<\/strong><\/span>
\n6x – 5y – 16 = 0
\n7x – 13y + 10 = 0
\nBy cross multiplication we have
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\nHence the solution is x = 6, y = 4
\nQuestion 5:<\/strong><\/span>
\n3x + 2y + 25 = 0
\n2x + y + 10 = 0
\nBy cross multiplication, we have
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\nHence the solution is x = 5, y = -20
\nQuestion 6:<\/strong><\/span>
\n2x + y – 35 = 0
\n3x + 4y – 65 = 0
\nBy cross multiplication, we have
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\nQuestion 7:<\/strong><\/span>
\n7x – 2y – 3 = 0
\nBy cross multiplication, we have
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\nHence x = 1, y = 2 is the solution
\nQuestion 8:<\/strong><\/span>
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\nQuestion 9:<\/strong><\/span>
\nax + by – (a – b) = 0
\nbx – ay – (a + b) = 0
\nBy cross multiplication, we have
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\nQuestion 10:<\/strong><\/span>
\n2ax + 3by – (a + 2b) = 0
\n3ax + 2by – (2a + b) = 0
\nBy cross multiplication, we have
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\nQuestion 11:<\/strong><\/span>
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\nBy cross multiplication, we have
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\nQuestion 12:<\/strong><\/span>
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\nBy cross multiplication, we have
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\nQuestion 13:<\/strong><\/span>
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\nBy cross multiplication we have
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\nQuestion 14:<\/strong><\/span>
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\nTaking
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\nu + v – 7 = 0
\n2u + 3v – 17 = 0
\nBy cross multiplication, we have
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\nHence the solution is
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\nQuestion 15:<\/strong><\/span>
\nLet
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\nin the equation
\n5u – 2v + 1 = 0
\n15u + 7v – 10 = 0
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\nQuestion 16:<\/strong><\/span>
\n<\/p>\nExercise 3D<\/span><\/strong><\/h3>\n
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\nQuestion 2:<\/strong><\/span>
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\nQuestion 3:<\/strong><\/span>
\n3x – 5y – 7 = 0
\n6x – 10y – 3 = 0
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\nHence the given system of equations is inconsistent
\nQuestion 4:<\/strong><\/span>
\n2x – 3y – 5 = 0, 6x – 9y – 15 = 0
\nThese equations are of the form
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\nHence the given system of equations has infinitely many solutions
\nQuestion 5:<\/strong><\/span>
\nkx + 2y – 5 = 0
\n3x – 4y – 10 = 0
\nThese equations are of the form
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\nThis happens when
\n\\(k\\neq \\frac { -3 }{ 2 }\\)
\nThus, for all real value of k other that , the given system equations will have a unique solution
\n(ii) For no solution we must have
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\nHence, the given system of equations has no solution if\u00a0\\(k=\\frac { -3 }{ 2 } \\)
\nQuestion 6:<\/strong><\/span>
\nx + 2y – 5 = 0
\n3x + ky + 15 = 0
\nThese equations are of the form of
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\nThus for all real value of k other than 6, the given system of equation will have unique solution
\n(ii) For no solution we must have
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\nTherefore k = 6
\nHence the given system will have no solution when k = 6.
\nQuestion 7:<\/strong><\/span>
\nx + 2y – 3 = 0, 5x + ky + 7 = 0
\nThese equations are of the form
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\n(i) For a unique solution we must have
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\nThus, for all real value of k other than 10
\nThe given system of equation will have a unique solution.
\n(ii) For no solution we must have
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\nHence the given system of equations has no solution if
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\nFor infinite number of solutions we must have
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\nThis is never possible since
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\nThere is no value of k for which system of equations has infinitely many solutions
\nQuestion 8:<\/strong><\/span>
\n8x + 5y – 9 = 0
\nkx + 10y – 15 = 0
\nThese equations are of the form
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\nClearly, k = 16 also satisfies the condition
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\nHence, the given system will have no solution when k = 16.
\nQuestion 9:<\/strong><\/span>
\nkx + 3y – 3 = 0 —-(1)
\n12x + ky – 6 = 0 —(2)
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\nThese equations are of the form
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\nHence, the given system will have no solution when k = -6
\nQuestion 10:<\/strong><\/span>
\n3x + y – 1 = 0
\n(2k – 1)x + (k – 1)y – (2k + 1) = 0
\nThese equations are of the form
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\nThus,
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\nHence the given equation has no solution when k = 2
\nQuestion 11:<\/strong><\/span>
\n(3k + 1)x + 3y – 2 = 0
\n(k2<\/sup> + 1)x + (k – 2)y – 5 = 0
\nthese equations are of the form
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\nThus, k = -1 also satisfy the condition
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\nHence, the given system will have no solution when k = -1
\nQuestion 12:<\/strong><\/span>
\nThe given equations are
\n3x – y – 5 = 0 —(1)
\n6x – 2y + k = 0—(2)
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\nEquations (1) and (2) have no solution, if
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\nQuestion 13:<\/strong><\/span>
\nkx + 2y – 5 = 0
\n3x + y – 1 = 0
\nThese equations are of the form
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\nThus, for all real values of k other than 6, the given system of equations will have a unique solution
\nQuestion 14:<\/strong><\/span>
\nx – 2y – 3 = 0
\n3x + ky – 1 = 0
\nThese equations are of the form of
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\nThus, for all real value of k other than -6, the given system of equations will have a unique solution
\nQuestion 15:<\/strong><\/span>
\nkx + 3y – (k – 3) = 0
\n12x + ky – k = 0
\nThese equations are of the form
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\nThus, for all real value of k other than , the given system of equations will have a unique solution
\nQuestion 16:<\/strong><\/span>
\n4x – 5y – k = 0, 2x – 3y – 12 = 0
\nThese equations are of the form
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\nThus, for all real value of k the given system of equations will have a unique solution
\nQuestion 17:<\/strong><\/span>
\n2x + 3y – 7 = 0
\n(k – 1)x + (k + 2)y – 3k = 0
\nThese are of the form
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\nThis hold only when
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\nNow the following cases arises
\nCase : I
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\nCase: II
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\nCase III
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\nFor k = 7, there are infinitely many solutions of the given system of equations
\nQuestion 18:<\/strong><\/span>
\n2x + (k – 2)y – k = 0
\n6x + (2k – 1)y – (2k + 5) = 0
\nThese are of the form
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\nFor infinite number of solutions, we have
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\nThis hold only when
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\nCase (1)
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\nCase (2)
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\nCase (3)
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\nThus, for k = 5 there are infinitely many solutions
\nQuestion 19:<\/strong><\/span>
\nkx + 3y – (2k +1) = 0
\n2(k + 1)x + 9y – (7k + 1) = 0
\nThese are of the form
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\nFor infinitely many solutions, we must have
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\nThis hold only when
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\nNow, the following cases arise
\nCase – (1)
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\nCase (2)
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\nCase (3)
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\nThus, k = 2, is the common value for which there are infinitely many solutions
\nQuestion 20:<\/strong><\/span>
\n5x + 2y – 2k = 0
\n2(k +1)x + ky – (3k + 4) = 0
\nThese are of the form
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\nFor infinitely many solutions, we must have
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\nThese hold only when
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\nCase I
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\nThus, k = 4 is a common value for which there are infinitely by many solutions.
\nQuestion 21:<\/strong><\/span>
\nx + (k + 1)y – 5 = 0
\n(k + 1)x + 9y – (8k – 1) = 0
\nThese are of the form
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\nFor infinitely many solutions, we must have
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\nQuestion 22:<\/strong><\/span>
\n(k – 1)x – y – 5 = 0
\n(k + 1)x + (1 – k)y – (3k + 1) = 0
\nThese are of the form
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\nFor infinitely many solution, we must now
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\nk = 3 is common value for which the number of solutions is infinitely many
\nQuestion 23:<\/strong><\/span>
\n(a – 1)x + 3y – 2 = 0
\n6x + (1 – 2b)y – 6 = 0
\nThese equations are of the form
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\nFor infinite many solutions, we must have
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\nHence a = 3 and b = -4
\nQuestion 24:<\/strong><\/span>
\n(2a – 1)x + 3y – 5 = 0
\n3x + (b – 1)y – 2 = 0
\nThese equations are of the form
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\nThese holds only when
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\nQuestion 25:<\/strong><\/span>
\n2x – 3y – 7 = 0
\n(a + b)x + (a + b – 3)y – (4a + b) = 0
\nThese equation are of the form
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\nFor infinite number of solution
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\nPutting a = 5b in (2), we get
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\nPutting b = -1 in (1), we get
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\nThus, a = -5, b = -1
\nQuestion 27:<\/strong><\/span>
\nThe given equations are
\n2x + 3y = 7 —-(1)
\na(x + y) – b(x – y) = 3a + b – 2 —(2)
\nEquation (2) is
\nax + ay – bx + by = 3a + b – 2
\n(a – b)x + (a + b)y = 3a + b -2
\nComparing with the equations
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\nThere are infinitely many solution
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\n2a + 2b = 3a – 3b and 3(3a + b – 2) = 7(a + b)
\n-a = -5b and 9a + 3b – 6 = 7a + 7b
\na = 5b and 9a – 7a + 3b – 7b = 6
\nor 2a – 4b = 6
\nor a – 2b = 3
\nthus equation in a, b are
\na = 5b —(3)
\na – 2b = 3 —(4)
\nputting a = 5b in (4)
\n5b – 2b = 3 or 3b = 3 \u00de b = 1
\nPutting b = 1 in (3)
\na = 5 and b = 1
\nQuestion 28:<\/strong><\/span>
\nWe have 5x – 3y = 0 —(1)
\n2x + ky = 0 —(2)
\nComparing the equation with
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\nThese equations have a non – zero solution if
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\n<\/p>\nExercise 3E<\/span><\/strong><\/h3>\n
\nLet the cost of 1 chair be Rs x and the cost of one table be Rs. y
\nThe cost of 5 chairs and 4 tables = Rs(5x + 4y) = Rs. 2800
\n5x + 4y = 2800 —(1)
\nThe cost of 4 chairs and 3 tables = Rs(4x + 3y) = Rs. 2170
\n4x + 3y = 2170 —(2)
\nMultiplying (1) by 3 and (2) by 4, we get
\n15x + 12y = 8400 —(3)
\n16x + 12y = 8680 —(4)
\nSubtracting (3) and (4), we get
\nx = 280
\nPutting value of x in (1), we get
\n5 \u00d7 280 + 4y = 2800
\nor 1400 + 4y = 2800
\nor 4y = 1400
\n\\(y=\\frac { 1400 }{ 4 } =350 \\)
\nThus, cost of 1 chair = Rs. 280 and cost of 1 table = Rs. 350
\nQuestion 2:<\/strong><\/span>
\nLet the cost of a pen and a pencil be Rs x and Rs y respectively
\nCost of 37 pens and 53 pencils = Rs(37x + 53y) = Rs 820
\n37x + 53y = 820 —(1)
\nCost of 53 pens and 37 pencils = Rs(53x + 37y) = Rs 980
\n53x + 37y = 980 —(2)
\nAdding (1) and (2), we get
\n90x + 90y = 1800
\nx + y = 20 —(3)
\ny = 20 – x
\nPutting value of y in (1), we get
\n37x + 53(20 – x) = 820
\n37x + 1060 – 53x = 820
\n16x = 240
\n\\(x=\\frac { 240 }{ 16} =15 \\)
\nFrom (3), y = 20 – x = 20 – 15 = 5
\nx = 15, y = 5
\nThus, cost of a pen = Rs 15 and cost of pencil = Rs 5
\nQuestion 3:<\/strong><\/span>
\nLet the number of 20 P and 25 P coins be x and y respectively
\nTotal number of coins x + y = 50
\ni.e., x + y = 50 —(1)
\n
\nMultiplying (1) by 5 and (2) by 1, we get
\n5x + 5y = 250 —(3)
\n4x + 5y = 230 —(4)
\nSubtracting (4) from (3), we get
\nx = 20
\nPutting x = 20 in (1),
\ny = 50 – x
\n= 50 – 20
\n= 30
\nHence, number of 20 P coins = 20 and number of 25 P coins = 30
\nQuestion 4:<\/strong><\/span>
\nLet the two numbers be x and y respectively.
\nGiven:
\nx + y = 137 —(1)
\nx – y = 43 —(2)
\nAdding (1) and (2), we get
\n2x = 180
\n\\(y=\\frac { 180\u00a0}{\u00a02} =90 \\)
\nPutting x = 90 in (1), we get
\n90 + y = 137
\ny = 137 – 90
\n= 47
\nHence, the two numbers are 90 and 47.
\n