Question

what is the solution of
x+y=7
2x-4y=8

Answer 1

we have a `y` in the first equation and a `-4y` in the second equation

adding them up gives: `y+(-4y) = -3y` which isn't 0 like we want

however we can change that `y` to `+4y` by multiplying by 4. Then notice how `4y + (-4y) = 0y = 0`

Answer 2

so it's 0?

Answer 3

to change the y to 4y, we have to multiply both sides of the first equation by 4

x+y=7
4*(x+y)=4*7
4x+4y = 28

Answer 4

This system

x+y=7
2x-4y=8


turns into

4x+4y=28
2x-4y=8

Answer 5

Do you see how to solve

4x+4y=28
2x-4y=8

??

Answer 6

i don't

Answer 7

would you subtract?

Answer 8

you add actually

Answer 9

add straight down


4x+4y=28
2x-4y=8
-----------
6x+0y = 36

so 6x = 36 which means x = ???

Answer 10

6

Answer 11

yes

Answer 12

now take that x value and plug it into any equation that has x and y in it

Answer 13

then solve for y

Answer 14

12-47=8? am i doing that right?

Answer 15

i mean 12-4y=8

Answer 16

yes now solve for y

Answer 17

is y 0?

Answer 18

no

Answer 19

try again