CBSE Class 10 Maths Pair of Linear Equations in Two Variables Previous Year Questions
Help your child master CBSE Class 10 Maths Pair of Linear Equations in Two Variables with this carefully curated collection of previous year questions sourced from real CBSE board papers spanning 2015–2025. Every question — from MCQs on consistency conditions to graphical and word-problem long answers — comes with a detailed step-by-step solution prepared by Angle Belearn’s verified CBSE Maths specialists.
CBSE Class 10 Maths Pair of Linear Equations in Two Variables — Questions with Solutions
Multiple Choice Questions (1 Mark Each)
Explanation: Rewriting both equations in standard form: $ 2x – 5y – 6 = 0 $ and $ -6x + 15y + 18 = 0 $.
$$\frac{a_1}{a_2} = \frac{2}{-6} = -\frac{1}{3}, \quad \frac{b_1}{b_2} = \frac{-5}{15} = -\frac{1}{3}, \quad \frac{c_1}{c_2} = \frac{-6}{18} = -\frac{1}{3}$$ Since $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} = \dfrac{c_1}{c_2} $, the given pair of equations represents coincident lines.
Explanation: On the y-axis, $ x = 0 $. Substituting into $ 3x – y = 3 $: $$3(0) – y = 3 \Rightarrow y = -3$$ Thus, the point of intersection is $ (0, -3) $.
Explanation: Cost of 1 chair = $ x $, cost of 1 table = $ y $.
3 chairs + 1 table = ₹900 gives: $ 3x + y = 900 $
5 chairs + 3 tables = ₹2100 gives: $ 5x + 3y = 2100 $

Explanation: Non-intersecting lines are parallel to each other — they have no solution (inconsistent system). The condition for parallel lines is: $$\frac{a_1}{a_2} = \frac{b_1}{b_2} \neq \frac{c_1}{c_2}$$
Explanation: From the given equations: $$\frac{a_1}{a_2} = \frac{6}{2} = 3, \quad \frac{b_1}{b_2} = \frac{-3}{-1} = 3, \quad \frac{c_1}{c_2} = \frac{10}{9}$$ Since $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} \neq \dfrac{c_1}{c_2} $, the lines are parallel.
Explanation: Substituting $ x = 1,\ y = 2 $ in the first equation: $$2(1) + 3(2) + a = 0 \Rightarrow 8 + a = 0 \Rightarrow a = -8$$ Substituting in the second equation: $$2(1) + 3(2) + b = 0 \Rightarrow 8 + b = 0 \Rightarrow b = -8$$ Now, $ 2a = 2(-8) = -16 $ and $ b = -8 $, giving $ 2a = b $. Hence Option (B).
Explanation: For two parallel lines $ a_1x + b_1y + c_1 = 0 $ and $ a_2x + b_2y + c_2 = 0 $: $$\frac{a_1}{a_2} = \frac{b_1}{b_2} \neq \frac{c_1}{c_2}$$ Checking Option (C): $ \dfrac{3}{-12} = \dfrac{-2}{8} = -\dfrac{1}{4} $, but $ \dfrac{5}{7} \neq -\dfrac{1}{4} $. ✓ Condition satisfied, so the lines are parallel.
Explanation: Rewriting: $ x – 2y – 3 = 0 $ and $ -3x + ky + 9 = 0 $.
$ a_1=1,\ b_1=-2,\ c_1=-3 $ and $ a_2=-3,\ b_2=k,\ c_2=9 $.
For infinitely many solutions: $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} = \dfrac{c_1}{c_2} $ $$\frac{1}{-3} = \frac{-2}{k} = \frac{-3}{9}$$ From $ \dfrac{-2}{k} = \dfrac{-3}{9} \Rightarrow 3k = 18 \Rightarrow k = 6 $.
Concept: For an inconsistent (no solution) system: $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} \neq \dfrac{c_1}{c_2} $.
Here $ a_1=3,\ b_1=1,\ c_1=-1 $ and $ a_2=2k-1,\ b_2=k-1,\ c_2=-(2k+1) $.
Setting $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} $: $$\frac{3}{2k-1} = \frac{1}{k-1} \Rightarrow 3(k-1) = 2k-1 \Rightarrow 3k-3 = 2k-1 \Rightarrow k = 2$$
Explanation: Subtracting equation (ii) from equation (i): $$(32x + 33y) – (33x + 32y) = 34 – 31 \Rightarrow -x + y = 3 \Rightarrow y = x + 3$$ Substituting $ y = x + 3 $ into equation (i): $$32x + 33(x+3) = 34 \Rightarrow 65x = -65 \Rightarrow x = -1$$ Then $ y = -1 + 3 = 2 $. Hence $ x = -1,\ y = 2 $.
Explanation: Angle sum of a triangle = 180°: $$x + (3x-2) + y = 180 \Rightarrow 4x + y = 182 \quad \text{…(i)}$$ From $ \angle C – \angle B = 9 $: $$y – (3x-2) = 9 \Rightarrow y – 3x = 7 \quad \text{…(ii)}$$ Subtracting (ii) from (i): $ 7x = 175 \Rightarrow x = 25^\circ $.
From (ii): $ y = 7 + 75 = 82^\circ $. And $ \angle B = 3(25)-2 = 73^\circ $.
Sum of greatest (82°) and smallest (25°) = 107°.
Explanation: For a unique solution, the two lines must intersect at exactly one point. The condition is: $$\frac{a_1}{a_2} \neq \frac{b_1}{b_2}$$ This is equivalent to $ a_1b_2 \neq a_2b_1 $, which is Option (B).
Short Answer Questions — 1 Mark
Comparing with standard form: $ a_1=3,\ b_1=1,\ c_1=-3 $ and $ a_2=6,\ b_2=k,\ c_2=-8 $.
For no solution (inconsistent): $$\frac{a_1}{a_2} = \frac{b_1}{b_2} \neq \frac{c_1}{c_2} \Rightarrow \frac{3}{6} = \frac{1}{k} \neq \frac{-3}{-8}$$ From $ \dfrac{3}{6} = \dfrac{1}{k} \Rightarrow \dfrac{1}{2} = \dfrac{1}{k} \Rightarrow k = 2 $.
Check: $ \dfrac{1}{2} \neq \dfrac{3}{8} $ ✓
Hence, the value of $k$ is 2.
$ a_1=1,\ b_1=2,\ c_1=-3 $ and $ a_2=5,\ b_2=k,\ c_2=7 $.
For inconsistency: $$\frac{a_1}{a_2} = \frac{b_1}{b_2} \neq \frac{c_1}{c_2} \Rightarrow \frac{1}{5} = \frac{2}{k} \neq \frac{-3}{7}$$ From $ \dfrac{1}{5} = \dfrac{2}{k} \Rightarrow k = 10 $.
Check: $ \dfrac{1}{5} \neq \dfrac{-3}{7} $ ✓
Hence, the value of $k$ is 10.
$3x – y – 5 = 0$ and $6x – 2y – p = 0$
For parallel lines: $$\frac{a_1}{a_2} = \frac{b_1}{b_2} \neq \frac{c_1}{c_2} \Rightarrow \frac{3}{6} = \frac{-1}{-2} \neq \frac{-5}{-p}$$ $$\frac{1}{2} = \frac{1}{2} \neq \frac{5}{p} \Rightarrow p \neq 10$$ Hence, $p$ can be any real number except 10.
Short Answer Questions — 2 Marks
For infinitely many solutions: $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} = \dfrac{c_1}{c_2} $
Equating $ \dfrac{a_1}{a_2} = \dfrac{c_1}{c_2} $: $$\frac{c}{12} = \frac{3-c}{-c} \Rightarrow -c^2 = 12(3-c) \Rightarrow -c^2 = 36 – 12c$$ $$c^2 – 12c + 36 = 0 \Rightarrow (c-6)^2 = 0 \Rightarrow c = 6$$ Verifying with $ \dfrac{b_1}{b_2} = \dfrac{c_1}{c_2} $: $ \dfrac{3}{6} = \dfrac{-3}{-6} = \dfrac{1}{2} $ ✓
Hence, the value of $c$ is 6.
$2x + 3y = 7$ and $(k + 1)x + (2k – 1)y = 4k + 1$
$ a_1=2,\ b_1=3,\ c_1=-7 $ and $ a_2=k+1,\ b_2=2k-1,\ c_2=-(4k+1) $.
For infinitely many solutions: $$\frac{a_1}{a_2} = \frac{b_1}{b_2} \Rightarrow \frac{2}{k+1} = \frac{3}{2k-1}$$ Cross-multiplying: $$2(2k-1) = 3(k+1) \Rightarrow 4k – 2 = 3k + 3 \Rightarrow k = 5$$ Hence, for $k = 5$, the pair of equations will have infinitely many solutions.
$ a_1=1,\ a_2=3,\ b_1=2,\ b_2=k $.
For a unique solution: $$\frac{a_1}{a_2} \neq \frac{b_1}{b_2} \Rightarrow \frac{1}{3} \neq \frac{2}{k} \Rightarrow k \neq 6$$ Hence, for all values of $k$ except $k = 6$, the given pair of equations has a unique solution.
Long Answer Questions — 3 Marks
Line 1: $ 2y – x = 8 \Rightarrow x = 2y – 8 $
| $ y $ | 0 | 4 | 5 |
|---|---|---|---|
| $ x = 2y-8 $ | −8 | 0 | 2 |
Line 2: $ 5y – x = 14 \Rightarrow x = 5y – 14 $
| $ y $ | 3 | 4 | 2 |
|---|---|---|---|
| $ x = 5y-14 $ | 1 | 6 | −4 |
Line 3: $ y – 2x = 1 \Rightarrow y = 1 + 2x $
| $ x $ | 0 | 1 | 2 |
|---|---|---|---|
| $ y = 1+2x $ | 1 | 3 | 5 |
Plotting and finding intersections graphically:

The co-ordinates of the vertices of the triangle are: $A(1,\ 3)$, $B(2,\ 5)$, $C(-4,\ 2)$.
| $ x $ | 6 | 0 | 3 |
|---|---|---|---|
| $ y $ | 0 | 2 | 1 |
Line 2: $ 2x – 3y = 12 \Rightarrow y = \dfrac{2x-12}{3} $
| $ x $ | 6 | 0 | 3 |
|---|---|---|---|
| $ y $ | 0 | −4 | −2 |
Line 3: $ x = 0 $ is the y-axis.

The points of intersection (vertices of the triangle) are: $A(6,\ 0)$, $B(0,\ 2)$, $C(0,\ -4)$.
Let expenditure of A = $ 19y $ and expenditure of B = $ 16y $.
Using Saving = Income − Expenditure and savings = ₹2550 each: $$8x – 19y = 2550 \quad \text{…(i)}$$ $$7x – 16y = 2550 \quad \text{…(ii)}$$ Multiplying (i) by 7 and (ii) by 8, then subtracting: $$56x – 133y = 17850$$ $$56x – 128y = 20400$$ $$\Rightarrow -5y = -2550 \Rightarrow y = 510$$ Substituting $ y = 510 $ in (i): $ 8x = 2550 + 9690 = 12240 \Rightarrow x = 1530 $.
Income of A = $ 8 \times 1530 = \textbf{₹12,240} $ per month.
Income of B = $ 7 \times 1530 = \textbf{₹10,710} $ per month.
(i) How many points of intersection does the pair of linear equations have in total? Justify your answer.
(ii) Find the equation that represents one of the lines of the above pair.
Since more than one point of intersection is given, the lines must be coincident (overlapping). Every point on one line is also on the other, so there are infinitely many common points.
(ii) Using the general form $ ax + by = c $ and substituting the two given points:
Point $ (6, 0) $: $ 6a = c \Rightarrow a = \dfrac{c}{6} $
Point $ (0, 2) $: $ 2b = c \Rightarrow b = \dfrac{c}{2} $
Substituting and dividing by $ c $: $$\frac{x}{6} + \frac{y}{2} = 1 \Rightarrow x + 3y = 6$$ One equation of the pair is $ x + 3y = 6 $.
From the first condition: $ 2x – 16 = \dfrac{y}{2} \Rightarrow 4x – y = 32 $ …(i)
From the second condition: $ \dfrac{x}{2} – 1 = \dfrac{y}{2} \Rightarrow x – y = 2 $ …(ii)
From (ii): $ x = y + 2 $. Substituting in (i): $$4(y+2) – y = 32 \Rightarrow 3y = 24 \Rightarrow y = 8$$ Then $ x = 10 $.
The two numbers are 10 and 8.
From sum condition: $ (10x+y) + (10y+x) = 66 \Rightarrow 11(x+y) = 66 \Rightarrow x + y = 6 $ …(i)
Digits differ by 2: either $ x – y = 2 $ …(ii) or $ y – x = 2 $ …(iii).
Case 1: Solving (i) and (ii): $ x = 4,\ y = 2 $. Number = 42.
Case 2: Solving (i) and (iii): $ y = 4,\ x = 2 $. Number = 24.
There are two such numbers: 42 and 24.
Since $ m = \dfrac{1}{x} = \dfrac{1}{2} \Rightarrow x = 2 $ and $ n = \dfrac{1}{y} = \dfrac{1}{3} \Rightarrow y = 3 $.
Final Answer: $ x = 2,\ y = 3 $.


Since BCDE forms a rectangle, $ \text{CD} = \text{BE} = 7 $: $$x + y = 7 \quad \text{…(1)}$$ Using the perimeter condition: $$AB + BC + CD + DE + AE = 27$$ $$5 + (x-y) + (x+y) + (x-y) + 5 = 27$$ $$3x – y + 10 = 27 \Rightarrow 3x – y = 17 \quad \text{…(2)}$$ From (1): $ y = 7 – x $. Substituting in (2): $$3x – (7-x) = 17 \Rightarrow 4x = 24 \Rightarrow x = 6,\quad y = 1$$ Final Answer: $ x = 6,\ y = 1 $.
Three years hence: Father’s age = $ 3x + 6 $, Son’s age = $ x + 3 $.
According to the condition: $$3x + 6 = 10 + 2(x + 3) \Rightarrow 3x + 6 = 2x + 16 \Rightarrow x = 10$$ Father’s present age: $ 3(10) + 3 = 33 $ years.
Son’s present age = 10 years; Father’s present age = 33 years.
Long Answer Questions — 5 Marks
| $ x $ | 6 | 1 | −4 |
|---|---|---|---|
| $ y $ | 0 | −1 | −2 |
Line 2: $ 2x – 10y = 12 \Rightarrow y = \dfrac{x-6}{5} $
| $ x $ | 6 | 1 | −4 |
|---|---|---|---|
| $ y $ | 0 | −1 | −2 |

Observation: Both equations represent the same line — the graphs coincide completely.
Condition of Consistency: The system has infinitely many solutions. The pair of linear equations is consistent and dependent.
The values are $ m = 5 $ and $ n = 1 $.
Total: $ x + y = 1500 $ …(i) X-A was ₹100 less: $ y – x = 100 $ …(ii)
From (i): $ y = 1500 – x $
| $ x $ | 0 | 700 | 1500 |
|---|---|---|---|
| $ y $ | 1500 | 800 | 0 |
From (ii): $ y = x + 100 $
| $ x $ | 0 | 700 | 500 |
|---|---|---|---|
| $ y $ | 100 | 800 | 600 |

The lines intersect at $ (700, 800) $.
Section X-A contributed ₹700 and Section X-B contributed ₹800.
From the first condition (3 chairs + 1 table = ₹1500): $$3x + y = 1500$$ From the second condition (6 chairs + 1 table = ₹2400): $$6x + y = 2400$$ The required pair of linear equations is $ 3x + y = 1500 $ and $ 6x + y = 2400 $.
Total coins: $ x + y = 50 $ …(i)
Total amount: $ x + 2y = 75 $ …(ii)
Subtracting (i) from (ii): $ y = 25 $. Substituting back: $ x = 25 $.
Number of ₹1 coins = 25 and Number of ₹2 coins = 25.
From condition 1: $ x = 3y $ …(i)
After five years: $ x + 5 = \dfrac{5}{2}(y + 5) \Rightarrow 2x + 10 = 5y + 25 \Rightarrow 2x = 5y + 15 $ …(ii)
Substituting (i) in (ii): $ 6y = 5y + 15 \Rightarrow y = 15 $. Then $ x = 45 $.
Sumit’s present age is 45 years.
Subtract (ii) from (iii): $$(9x – 15y) – (9x – 2y) = 12 – 7 \Rightarrow -13y = 5 \Rightarrow y = -\frac{5}{13}$$ Substituting in (i): $ 3x = 4 + 5\left(-\dfrac{5}{13}\right) = 4 – \dfrac{25}{13} = \dfrac{27}{13} \Rightarrow x = \dfrac{9}{13} $.
Final Answer: $ x = \dfrac{9}{13},\ y = -\dfrac{5}{13} $.
Find at least one pair of possible values of $m$ and $n$, if they exist, for which the above pair has:
(i) a unique solution (ii) infinitely many solutions (iii) no solution
(i) Unique Solution — need $ \dfrac{m}{n} \neq \dfrac{1}{2} $.
Take $ m = 2,\ n = 6 $: $ \dfrac{2}{6} = \dfrac{1}{3} \neq \dfrac{1}{2} $ ✓
Equations become $ 2x – 2y = 9 $ and $ 4x – 6y = 9 $. One valid pair: $ m = 2,\ n = 6 $.
(ii) Infinitely Many Solutions — need $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} = \dfrac{c_1}{c_2} $, i.e., $ \dfrac{1}{2} = \dfrac{m}{n} = 1 $.
But $ \dfrac{1}{2} \neq 1 $, so this condition is impossible.
No such values of $m$ and $n$ exist for infinitely many solutions.
(iii) No Solution — need $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} \neq \dfrac{c_1}{c_2} $, i.e., $ \dfrac{m}{n} = \dfrac{1}{2} $ and $ \dfrac{c_1}{c_2} = 1 \neq \dfrac{1}{2} $ ✓
Take $ m = 3,\ n = 6 $: $ \dfrac{3}{6} = \dfrac{1}{2} $ and $ \dfrac{c_1}{c_2} = 1 \neq \dfrac{1}{2} $ ✓
Equations become $ 2x – 3y = 9 $ and $ 4x – 6y = 9 $. One valid pair: $ m = 3,\ n = 6 $.
Additional Multiple Choice Questions (2025 Board)
Explanation: Substituting $ x=1,\ y=2 $ in the first equation: $$2(1) – 3(2) + a = 0 \Rightarrow 2 – 6 + a = 0 \Rightarrow a = 4$$ Substituting in the second equation: $$2(1) + 3(2) – b = 0 \Rightarrow 8 – b = 0 \Rightarrow b = 8$$ Now, $ 2a = 2(4) = 8 = b $. Hence $ 2a = b $, which is Option (B).
Explanation: For no solution (parallel lines), $ \dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} \neq \dfrac{c_1}{c_2} $.
$$\frac{5}{2} = \frac{2}{k} \Rightarrow 5k = 4 \Rightarrow k = \frac{4}{5}$$ Check: $ \dfrac{-7}{1} \neq \dfrac{5}{2} $ ✓. Hence $ k = \dfrac{4}{5} $, which is Option (B).
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