Question

Solve the equations using elimination method:
$5x+6y=9$ and $x-y=4$

• A. (-3, -1)
• B. (3, -1)
• C. (-3, 2)
• D. (3, 1)

Answer 1

The correct option is B (3, -1)

Multiply equation (2) by 6 and then subtract equation 1 and 2,
$5x+6y=9$ ----- (1)
$x-y=4$ ----- (2)
$5x+6y=96$
$6x-6y=24$
______________
$11x=33$
$x=\frac{33}{11}=3$
Put the value of x in equation (1), we get
$5x+6y=9$
$5\left(3\right)+6y=9$
$15+6y=9$
$6y=9-15$
$y=\frac{-6}{6}=-1$
Therefore the solution is (3, -1)