MathsCBSE Class 10 · Standard · Board exam 2025, set 30/1/1 · 1 mark · MCQ

CBSE Class 10 Mathematics Standard 2025: question 2

Set in the CBSE Class 10 board exam of 2025, paper 30/1/1, section A, question 2, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q2 · 1 mark · MCQPair of Linear Equations in Two Variables

If $x = 1$ and $y = 2$ is a solution of the pair of linear equations $2 x - 3 y + a = 0$ and $2 x + 3 y - b = 0$ , then :

(A) $a = 2 b$
(B) $2 a = b$
(C) $a + 2 b = 0$
(D) $2 a + b = 0$

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 30/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

A solution satisfies both equations.

Hint 2

Substitute $x = 1, y = 2$ into each equation to find $a$ and $b$ , then compare them.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

Put $x = 1, y = 2$ in the first equation: $2 - 6 + a = 0 \Rightarrow a = 4$ .
Put $x = 1, y = 2$ in the second equation: $2 + 6 - b = 0 \Rightarrow b = 8$ .
Since $b = 8 = 2 \times 4$ , we get $2 a = b$ , which is option (B).
1 mark

Answer: 2a = b, option (B)

Where the marks are

Finds $a = 4$ and $b = 8$ and concludes $2 a = b$ , option (B) (1 mark)

Revise the chapter

Chapter: Pair of Linear Equations in Two Variables (notes, formulas, where marks are lost and every past question)

Practise this chapterBoard-style questions from Pair of Linear Equations in Two Variables, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 30/1/1 (Standard): every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.

CBSE Class 10 Mathematics Standard 2025: question 2

Hints

Step-by-step solution

Revise the chapter

More questions from Pair of Linear Equations in Two Variables