Question

Use elimination to solve the following system of equations.
4x+7y=-16
-12x-7y=-8

A.(7, -8)
B.(-4, 3)
C.(8, -7)
D.(3, -4)

Answer 1

Elimination is you eliminate one variable by manipulation the equations. In the above set of equations if you just add them together variable y gets eliminated. because one has +7y and the other has -7y.

Now if you add both equations you get

4x +( -12x) + 7y + (-7y) = -16 +( -8)
-8x = -24
x = -24/-8 = 3

Now only answer choice is d (3, -4)

pf you had 2 choices that had x = 3, then substitue x=3 in one equation and find y

Answer 2

The y's cancel and your left with:
4x=-16
-12x=-8

Add down and you get:
-8x=-24

Divide and you get
x=3

plug in 3 into x in the beginning equation and the only possible choice is D