How do you solve 3x+4y=0 and x-4y= -8?

1 Answer
Alan P.
Mar 5, 2018

x=-2 and y=3/2

Explanation:

Given
[1]color(white)("XXX")3x+4y=0
[2]color(white)("XXX")x-4y=-8

Adding equations [1] and [2] together
[3]color(white)("XXX")4x=-8

Dividing both sides of [3] by 4
[4]color(white)("XXX")x=-2

Substituting (-2) for x back in [2]
[5]color(white)("XXX")(-2)-4y=-8

rarr[6]color(white)("XXX")-4y=-6

rarr[7]color(white)("XXX")y=3/2 ...or if you prefer a mixed number y=1 1/2

Related questions
See all questions in Linear Systems with Multiplication
Impact of this question
3023 views around the world
You can reuse this answer
Creative Commons License