Question

Solve the system of equations by the addition method.



Choose one answer.
a. (-2, 1)
b. (-2, -1)
c. (2, 1)
d. (2, -1)

Answer 1

THe addition method is adding one term to another to get a variable to cancel out.

Answer 2

You can multiply the equations by various numbers first to get the variables just right so they cancel

Answer 3

It doesn't matter what variable we choose to cancel out. Let's do x

Answer 4

ok!

Answer 5

We need the number in front of the first x to be the opposite of the second x, like 5, -5, or -3, 3, so they'll add to zero.

Answer 6

Lets multiply the first equation by 5 and the second one by -3 so we'll get a 15x and a -15x

Answer 7

5(-3x+7y=-1)
-15x+35y=-5

Answer 8

second equation: -3(-5x-4y=14)
15x+12y=-42

Answer 9

Do you see what I did there?

Answer 10

wynwyn? uthere?

Answer 11

Yes yes yes i see!!

Answer 12

kk... now u just add the equations together.
-15x+35y=-5
+
15x=12y=-42

Answer 13

(4 second equation: supposed to be 15x+12y=-42)

Answer 14

so. -15x+15x=0.
35y+12y=47y
-5+-42=-47
0+47y=-47

Answer 15

Now just solve for y.
47y=-47
y=-1

Answer 16

Now that u know what y is, plug it back into an equation (it doesn't matter which) and solve for x

Answer 17

-3x+7y=-1
-3x+7(-1)=-1
-3x-7=-1
-3x=6
x=-2

Answer 18

ok

Answer 19

It looks like you want your final answer to be an ordered pair, like a point on a graph. a point is always in the form (x,y), so your final answer is -2,-1

Answer 20

choice b

Answer 21

Thank you so much!!!

Answer 22

welcome! Medal?

Answer 23

tnx :)

Answer 24

no problem! =D