Question

$3x–4y=1$...(1)
$5x–6y=7$...(2)
In the above equations, which of the following step can to be done to numerically equate the coefficients of $x$?

• A. Multiply equation (1) by 6 and equation (2) by 4.
• B. Multiply equation (1) by 3 and equation (2) by 5.
• C. Multiply equation (1) by 5 and equation (2) by 3.
• D. Multiply equation (1) by 4 and equation (2) by 6.

Answer 1

The correct option is C

Multiply equation (1) by 5 and equation (2) by 3.

Coefficient of $x$ in equation (1) is 3.

Coefficient of $x$ in equation (2) is 5.

So, to make coefficients of $x$ equal, multiply equation (1) by 5 and equation (2) by 3.

Equation (1) × 5 $\Rightarrow 15x–20y=5$

Equation (2) × 3 $\Rightarrow 15x–18y=21$