Question

4x+7y=-80
3x+5y=-58
elimination using multiplacation.

Answer 1

First, lets cancel the x's, by doing this, we need to multiply the first equation by 3 and the second equation by -4.

4x+7y=-80 -----> Multiplied by 3
3x+5y=-58 -----> Multiplied by -4

Can you tell me what each equation will be now? :o)

Answer 2

12x+28y=-80
-12x +20y=-58

Answer 3

4x+7y=-80 -----> 12x+21y= -240
3x+5y=-58 ----> -12x-20y = 232

Now we're going to add like this:

12x+21y= -240
+ -12x-20y = 232
---------------
y= -8

Notice how we multiplied the equations so that the value of x would cancel out so we could find the value of y. Do you see how we did that?

Answer 4

yeah, and x, we do the opposite with. replacing y's with -8's.

Answer 5

Right, so replace the y with -8 in the first original equation: 4x+7y=-80

So it'd be: 4x+7(-8)=-80

Now, solve for x. Do you know how? :o)

Answer 6

x=6.

Answer 7

Remeber, ALWAYS replace in the ORIGINAL equation or your answer wont be correct. :o)

4x-56=-80
4x=-24
x= -6

I think you forgot the negative sign. :o) But great work :o)

Answer 8

THANK YOU. so much better than my teacher.

Answer 9

Anytime :o) If you ever need any other help just holler. :o)