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

Question

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

Accepted Answer

## Model Answer Substituting $x = 1$, $y = 2$ in $2x - 3y + a = 0$: $2 - 6 + a = 0 \Rightarrow a = 4$. Substituting in $2x + 3y - b = 0$: $2 + 6 - b = 0 \Rightarrow b = 8$. Thus $2a = 8 = b$, so **Option B: $2a = b$**. ## Explanation Substitute the given solution into both equations to find $a$ and $b$ separately, then check which option satisfies the relationship. Here $a = 4$ and $b = 8$, giving $2a = b$. Examiners expect you to show the substitution step clearly, even in MCQs, to earn full credit.

Mathematics — CBSE Class 10 board question