Question

Find the solution of the given pair of equations
$2x+3y=9,3x+4y=5$

• A. x = 21, y = 7
• B. x = - 21, y = 17
• C. x = 19, y = 14
• D. x = 20, y = 12

Answer 1

The correct option is B

x = - 21, y = 17

Given,

$2x+3y=9$ ...(1)

$3x+4y=5$ ...(2)

Multiply equation (1) with 3

$6x+9y=27$ ...(3)

Multiply equation (2) with 2

$6x+8y=10$ ...(4)

Subtracting (4) from (3):

$y=17$

Substituting $y=17$ in (1), we get

$2x+3\left(17\right)=9$

$\Rightarrow 2x=9-51=-42\Rightarrow .x=\frac{-42}{2}=-21$

$\therefore x=-21,y=17$