How do you solve the following system: -3x + y = -4, 4x + 2y = 0 ?

1 Answer
Mar 16, 2016

x=4/5 and y=-8/5

Explanation:

we begin with -3x+y=-4 and 4x+2y=0

Now, I'm going to solve for y in -3x+y=-4 which looks like y=-4+3x.

So no we can replace the y in the second equation with -4+3x.

That gives us 4x+2(-4+3x)=0 which we can simplify to 4x-8+6x=0. This becomes 10x=8 or x=4/5.

No, we can solve for y.

y=-4+3(4/5), which is -4+12/5 or -8/5.

Now we should double check our math. If we did this right then 4(4/5)+2(-8/5) should equal 0. Let's see if it is: 16/5-16/5 does in fact equal 0, which means that we were right!

Nice Job!