Question

i need to solve systems by substitution, can someone walk me through this?
y - 2x = -5
y - x = -3

Answer 1

pick one equation and solve for any variable. I'm going to solve y - x = -3 for y

y - x = -3

y - x+x = -3+x

y = x - 3

Answer 2

then focus on the other equation and plug y = x-3 into it

y - 2x = -5

x-3 - 2x = -5 ... replace every copy of y with x-3

-x-3 = -5

...
...
...

x = ???

Answer 3

so im still confused, idk where i substitute the Y

Answer 4

what do you mean? which part?

Answer 5

like i know if you solve for x then you substitute it in like 2(x-3) blah blah blah like that right?

Answer 6

do you see how I got y = x-3 ?

Answer 7

you removed it from the left side and put it on the right?

Answer 8

make y=x-3
(x-3) -2x=5

Answer 9

I isolated y in y - x = -3 to get y = x-3

Answer 10

x-3-2x=5
-x-3=5
x=-8
so y=8-3
y=5

Answer 11

then you substitute the y in for the next equation to get x?

Answer 12

@Kamil69 ?

Answer 13

Kamil69 it should be

y = x-3

y = -8-3

y = -11

Answer 14

y dosent equal 5 its -11?

Answer 15

yes you are right y=-11

Answer 16

now we substitute? -11 -2x = -5?

Answer 17

@jim_thompson5910

Answer 18

You're done. You found x = -8 and y = -11.

Answer 19

i dont know how we found x..

Answer 20

because y=x-3
so y= -8-3
y=-11
so you can check your answer by y-2x=5
-11-2(-8)=5
-11+16=5
5=5

Answer 21

Kamil69 shows you how in the steps above

Answer 22

can we do a couple more together so i can figure ouut how to do this on my own?

Answer 23

i have assignment do tonight, but i can help you tomorrow if you want

Answer 24

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

Answer 25

make y=4-2x

Answer 26

ok i got that part

Answer 27

so put back in first equation

Answer 28

2x(4-2x) = -8?

Answer 29

you should have 2x-(4-2x)=-8

Answer 30

ok

Answer 31

now 2x-4+2x=-8

Answer 32

-8x - 4x = -8

Answer 33

no

Answer 34

4x-4=-8

Answer 35

kk

Answer 36

4x = -4

Answer 37

x = -1?

Answer 38

4x=-8+4

Answer 39

4x=-4
so x=-1

Answer 40

then sub it in for the next equation 2(-1) - y = -8

Answer 41

no you dont have because wes have y=4-2x
y=4-2(-1)
y=4+2
y=6

Answer 42

ok im starting to get it...one more pls?
x + y =2
3x -2y =6

Answer 43

i got y = -5

Answer 44

-3, -5?

Answer 45

@Kamil69

Answer 46

no y=0
x=2