Question

Solve the systems of equations using elimination.
4x-y=105
x+7y=-10

Answer 1

if you want to eliminate, make one variable same coefficient. lets take x. so second eq. should multiply by 4. then first eq. minus second eq..

Answer 2

4x+28=-40
second eq should be like this.

Answer 3

4(4x-y=105)

no I'm sure you have to add the equations, not subtract.

Answer 4

oh its ok to add or subtract in elimination

Answer 5

if you want to add variable y should have same coefficient

Answer 6

we can try both.

Answer 7

ok.
4x-y=105
-4(x+7y=-10)
-4x-28y=40

right?

Answer 8

this also correct.

Answer 9

you know next step right? just add both of them

Answer 10

yeah. but that will leave me with -y-28y=145. what is -y-28y?

Answer 11

-y-28y=-29y.

Answer 12

rightttt. thanks.

y=-5. right?

Answer 13

yes

Answer 14

sure you know x too

Answer 15

yeah i know how to solve for x. I'll give you the answer, tell me if it's right.

Answer 16

x=25?

Answer 17

yes. good job

Answer 18

thank you!