Question

What is the solution of the system? Use substitution.

3x + 2y = 7
y = –3x + 11
A.
(6, -3)

B.
(6, -7)

C.
(-4,19/2)
D. (5,-4)

Answer 1

@Qwertty123 @alexandrea.lane

Answer 2

Hey, what do you think we do first?

Answer 3

factor?

Answer 4

No, when substituting we are trying to get x/y alone and plug it back in to get x/y alone. So basically we are trying to get 2 points to graph.

Answer 5

ok. how do i do that

Answer 6

Well, they already set it equals to Y for us so all we do is plug Y in into the first equation.

What would we do?

Answer 7

subtract 11 and 3x?

Answer 8

i have no idea

Answer 9

3x + 2y =7
Y = -3x + 11
adding them:

Answer 10

2y+11=y+7

Answer 11

Here is a better explanation "The method of solving "by substitution" works by solving one of the equations (you choose which one) for one of the variables (you choose which one), and then plugging this back into the other equation, "substituting" for the chosen variable and solving for the other. Then you back-solve for the first variable."

Answer 12

3x + 2y = 7
y = –3x + 11

Plug it in for Y and get

3x+2(-3x+11)=7

Answer 13

So, what do we do first in the equation?

Answer 14

so distribute?

Answer 15

Yes, what do we get?

Answer 16

-6x+22???

Answer 17

Correct so we have
3x-6x+22=7

What do we do next?

Answer 18

-3x+22=7?

Answer 19

-22?

Answer 20

-22? what do you mean?

Answer 21

-3x=-15 divide by -3= 5?

Answer 22

What do we get?

Answer 23

5

Answer 24

COrrect :D what do we do next?

Answer 25

i have no idea

Answer 26

5,-4???

Answer 27

Now, we plug 5 into the equation to get Y

y = –3(5) + 11

Answer 28

ok

Answer 29

What do we get?

Answer 30

-4

Answer 31

Correct :D Great job so the answer is ?

Answer 32

5,-4 is answer

Answer 33

thanks

Answer 34

Correct