Pair of Linear Equations in Two Variables: 2 marks Questions (CBSE Class 10)
30 different 2 marks questions on Pair of Linear Equations in Two Variables from CBSE Class 10 Maths board exams 2022–2026, newest first.
Solve the following system of equations for x and y :2 x + 3 2 y = − 1 and x − 3 y = 3
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Answer: x = 2 , y = − 3
Multiply the first equation by 6: 3 x + 4 y = − 6 ... (1) Multiply the second equation by 3: 3 x − y = 9 ... (2) (1) − (2): 5 y = − 15 , so y = − 3 . From (2): 3 x = 9 + y = 6 , so x = 2 .
Solve for x and y :0.1 x + 0.3 y = 1 0.2 x − 0.1 y = − 0.1
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Answer: x = 1 , y = 3
Multiply both equations by 10: x + 3 y = 10 ... (1) and 2 x − y = − 1 ... (2) From (2): y = 2 x + 1 . Substitute in (1): x + 6 x + 3 = 10 , so 7 x = 7 and x = 1 . y = 2 ( 1 ) + 1 = 3 .
Solve for x and y :3 x + 5 y = 8 5 x − 3 y = 2
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Answer: x = 1 , y = 1
Multiply the first equation by 3 and the second by 5: 9 x + 15 y = 24 and 25 x − 15 y = 10 . Adding: 34 x = 34 , so x = 1 . Then 3 + 5 y = 8 , so y = 1 .
Find the value of c for which the following pair of linear equations has infinitely many solutions :c x + 3 y = c − 3 12 x + cy = c
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Answer: c = 6
Write as c x + 3 y − ( c − 3 ) = 0 and 12 x + cy − c = 0 . For infinitely many solutions: 12 c = c 3 = c c − 3 . From 12 c = c 3 : c 2 = 36 , so c = 6 or c = − 6 . From c 3 = c c − 3 : 3 = c − 3 , so c = 6 . Check c = 6 : 12 6 = 6 3 = 6 3 = 2 1 . So c = 6 .
Solve for x and y :3 x + 2 y = 65 2 x + 3 y = 60
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Answer: x = 15 , y = 10
Adding: 5 x + 5 y = 125 ⇒ x + y = 25 . Subtracting: x − y = 5 . Adding these: 2 x = 30 ⇒ x = 15 ; then y = 10 . Check: 45 + 20 = 65 , 30 + 30 = 60 .
Solve the following system of equations graphically :2 x − 3 y = − 6 and x = 3
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Answer: x = 3 , y = 4
2 x − 3 y = − 6 : points ( 0 , 2 ) , ( − 3 , 0 ) , ( 3 , 4 ) . Plot and join them.x = 3 : a vertical line through ( 3 , 0 ) , parallel to the y-axis.The two lines meet at ( 3 , 4 ) . Hence x = 3 , y = 4 .
Solve the following system of equations graphically :x + 2 y = 10 and y = 3
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Answer: x = 4 , y = 3
x + 2 y = 10 : points ( 0 , 5 ) , ( 10 , 0 ) , ( 4 , 3 ) . Plot and join them.y = 3 : a horizontal line through ( 0 , 3 ) , parallel to the x-axis.The two lines meet at ( 4 , 3 ) . Hence x = 4 , y = 3 .
Solve the following system of linear equations graphically :x + y = 5 and x − y = 3
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Answer: x = 4 , y = 1
x + y = 5 : points ( 0 , 5 ) , ( 5 , 0 ) , ( 4 , 1 ) . Plot and join them.x − y = 3 : points ( 3 , 0 ) , ( 0 , − 3 ) , ( 4 , 1 ) . Plot and join them.The two lines meet at ( 4 , 1 ) . Hence x = 4 , y = 1 .
Solve the following system of equations algebraically :30 x + 44 y = 10 ; 40 x + 55 y = 13
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Answer: x = 5 1 , y = 11 1
Multiply the first equation by 4: 120 x + 176 y = 40 Multiply the second equation by 3: 120 x + 165 y = 39 Subtract: 11 y = 1 , so y = 11 1 Substitute: 30 x + 4 = 10 , so x = 5 1 Check: 40 × 5 1 + 55 × 11 1 = 8 + 5 = 13
Solve the following system of equations algebraically :37 x + 63 y = 137 63 x + 37 y = 163
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Answer: x = 2 , y = 1
Add: 100 x + 100 y = 300 ⇒ x + y = 3 ... (1) Subtract the first from the second: 26 x − 26 y = 26 ⇒ x − y = 1 ... (2) From (1) and (2): x = 2 , y = 1 Check: 37 ( 2 ) + 63 ( 1 ) = 137
Solve the following system of equations algebraically :73 x − 37 y = 109 37 x − 73 y = 1
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Answer: x = 2 , y = 1
Subtract: 36 x + 36 y = 108 ⇒ x + y = 3 ... (1) Add: 110 x − 110 y = 110 ⇒ x − y = 1 ... (2) From (1) and (2): x = 2 , y = 1 Check: 73 ( 2 ) − 37 ( 1 ) = 109 , 37 ( 2 ) − 73 ( 1 ) = 1
The cost of 2 kg apples and 1 kg of grapes on a day was found to be ₹ 320. The cost of 4 kg apples and 2 kg grapes was found to be ₹ 600. If cost of 1 kg of apples and 1 kg of grapes is ₹ x and ₹ y respectively, represent the given situation algebraically as a system of equations and check whether the system so obtained is consistent or not.
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Answer: 2 x + y = 320 , 4 x + 2 y = 600 ; the system is inconsistent.
Equations: 2 x + y = 320 and 4 x + 2 y = 600 a 2 a 1 = 4 2 = 2 1 , b 2 b 1 = 2 1 , c 2 c 1 = 600 320 = 15 8 a 2 a 1 = b 2 b 1 = c 2 c 1 , so the lines are parallel.The system has no solution: it is inconsistent.
Solve for x and y :2 x + 3 y = 5 and3 x − 8 y = − 6
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Multiply the first equation by 3 : 6 x + 3 y = 5 3 ... (1) Multiply the second equation by 2 : 6 x − 4 y = − 2 3 ... (2) (1) − (2): 7 y = 7 3 ⇒ y = 3 Then 2 x + 3 = 5 ⇒ x = 2 2 = 2 Check: 3 ⋅ 2 − 2 2 ⋅ 3 = − 6 ✓
Solve the following pair of equations algebraically :101 x + 102 y = 304 102 x + 101 y = 305
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Answer: x = 2 , y = 1
Adding: 203 x + 203 y = 609 ⇒ x + y = 3 ... (1) Subtracting the first from the second: x − y = 1 ... (2) Adding (1) and (2): 2 x = 4 ⇒ x = 2 From (1): y = 1
In a pair of supplementary angles, the greater angle exceeds the smaller by 5 0 ∘ . Express the given situation as a system of linear equations in two variables and hence obtain the measure of each angle.
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Answer: x + y = 180 , x − y = 50 ; angles are 11 5 ∘ and 6 5 ∘
Let the greater angle be x ∘ and the smaller be y ∘ . Supplementary: x + y = 180 ... (1) Greater exceeds smaller by 5 0 ∘ : x − y = 50 ... (2) Adding: 2 x = 230 ⇒ x = 115 ; then y = 65 The angles are 11 5 ∘ and 6 5 ∘ .
Solve the following pair of linear equations for x and y algebraically :x + 2 y = 9 and y − 2 x = 2
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Answer: x = 1 , y = 4
From the first equation, x = 9 − 2 y . Substitute in the second: y − 2 ( 9 − 2 y ) = 2 , so 5 y − 18 = 2 and y = 4 . Then x = 9 − 8 = 1 .
Check whether the point ( − 4 , 3 ) lies on both the lines represented by the linear equations x + y + 1 = 0 and x − y = 1 .
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Answer: No; it lies on x + y + 1 = 0 but not on x − y = 1 .
For x + y + 1 = 0 : − 4 + 3 + 1 = 0 , so the point lies on this line. For x − y = 1 : − 4 − 3 = − 7 = 1 , so it does not lie on this line. Hence the point does not lie on both lines.
The sum of two natural numbers is 70 and their difference is 10. Find the natural numbers.
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Answer: 40 and 30
Let the numbers be x and y (x > y ). x + y = 70 and x − y = 10 Adding: 2 x = 80 , so x = 40 y = 70 − 40 = 30 The numbers are 40 and 30.
Solve for x and y :x − 3 y = 7 3 x − 3 y = 5
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Answer: x = − 1 , y = − 3 8
Subtract the first equation from the second: ( 3 x − 3 y ) − ( x − 3 y ) = 5 − 7 2 x = − 2 , so x = − 1 Then − 1 − 3 y = 7 , so − 3 y = 8 y = − 3 8
Solve the following system of linear equations7 x − 2 y = 5 and 8 x + 7 y = 15 and verify your answer.
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Answer: x = 1 , y = 1
7 x − 2 y = 5 ... (1), 8 x + 7 y = 15 ... (2)(1) × 7 : 49 x − 14 y = 35 ; (2) × 2 : 16 x + 14 y = 30 . Adding: 65 x = 65 , so x = 1 . From (1): 7 − 2 y = 5 , so y = 1 . Verification: 7 ( 1 ) − 2 ( 1 ) = 5 and 8 ( 1 ) + 7 ( 1 ) = 15 . Both equations hold.
Solve the following system of linear equations :2 p + 3 q = 13 and 5 p − 4 q = − 2
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Answer: p = 2 , q = 3
2 p + 3 q = 13 ... (1), 5 p − 4 q = − 2 ... (2)(1) × 4 : 8 p + 12 q = 52 ; (2) × 3 : 15 p − 12 q = − 6 . Adding: 23 p = 46 , so p = 2 . From (1): 4 + 3 q = 13 , so q = 3 .
Solve the following system of linear equations algebraically :2 x + 5 y = − 4 ; 4 x − 3 y = 5
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Answer: x = 2 1 , y = − 1
2 x + 5 y = − 4 ... (1), 4 x − 3 y = 5 ... (2)(1) × 2 : 4 x + 10 y = − 8 ... (3) (3) − (2): 13 y = − 13 , so y = − 1 . From (1): 2 x − 5 = − 4 , so x = 2 1 .
If 2 x + y = 13 and 4 x − y = 17 , find the value of ( x − y ) .
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Answer: x − y = 2
Adding the equations: 6 x = 30 , so x = 5 . Then y = 13 − 2 ( 5 ) = 3 . x − y = 5 − 3 = 2 .
Sum of two numbers is 105 and their difference is 45. Find the numbers.
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Answer: 75 and 30
Let the numbers be x and y with x > y . x + y = 105 and x − y = 45 .Adding: 2 x = 150 , so x = 75 ; then y = 105 − 75 = 30 . The numbers are 75 and 30.
Solve for x and y : x + y = 6 , 2 x − 3 y = 4 .
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Answer: x = 5 22 , y = 5 8
From the first equation, x = 6 − y . Substitute: 2 ( 6 − y ) − 3 y = 4 , so 12 − 5 y = 4 . y = 5 8 x = 6 − 5 8 = 5 22
Find out whether the following pair of linear equations are consistent or inconsistent :5 x − 3 y = 11 , − 10 x + 6 y = 22
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Answer: Inconsistent
Write as 5 x − 3 y − 11 = 0 and − 10 x + 6 y − 22 = 0 . a 2 a 1 = − 10 5 = − 2 1 , b 2 b 1 = 6 − 3 = − 2 1 , c 2 c 1 = − 22 − 11 = 2 1 a 2 a 1 = b 2 b 1 = c 2 c 1 , so the lines are parallel.The pair has no solution, so it is inconsistent.
Solve the pair of equations x = 3 and y = − 4 graphically.
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Answer: x = 3, y = –4, i.e. the lines meet at (3, –4).
x = 3 is a line parallel to the y-axis through (3, 0).y = − 4 is a line parallel to the x-axis through (0, –4).Draw both lines; they intersect at (3, –4). Solution: x = 3 , y = − 4 .
Using graphical method, find whether following system of linear equations is consistent or not :x = 0 and y = − 7
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Answer: Consistent; the lines meet at (0, –7).
x = 0 is the y-axis.y = − 7 is a line parallel to the x-axis through (0, –7).The two lines intersect at exactly one point (0, –7). So the system has a unique solution and is consistent.
Solve the pair of equations x = 5 and y = 7 graphically.
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Answer: x = 5, y = 7, i.e. the lines meet at (5, 7).
x = 5 is a line parallel to the y-axis through (5, 0).y = 7 is a line parallel to the x-axis through (0, 7).Draw both lines; they intersect at (5, 7). Solution: x = 5 , y = 7 .
Using graphical method, find whether pair of equations x = 0 and y = − 3 , is consistent or not.
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Answer: Consistent; the lines meet at (0, –3).
x = 0 is the y-axis.y = − 3 is a line parallel to the x-axis through (0, –3).The two lines intersect at exactly one point (0, –3). So the pair has a unique solution and is consistent.
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