Question

solve the linear system by using elimination, -3x-y=-15, 8x+4y=48.

Answer 1

Elimination method

-3x+y = 15 -----> (1)

8x+4y = 48 -------> (2)

Multiplr to each side of equation (1) by4.

-12x+4y = 60 --------> (3)

To eliminate the y value subtract equation (3) from (2).

-12x+4y = 60

8x+4y = 48

(-) (-)    (-)

_________

 -20x = 12

Divide to each side by negitive 20.

-20x/-20 = 12/-20

⇒ x = -3/5

Substitute the x value in (1)

-3*-3/5+y = 15

9/5+y = 15

Subtrac 9/5 from each side.

9/5-9/5+y = 15-9/5

y = 75-9/5

⇒ y = 66/5

Solution is x= -3/5, y = 66/5.