Question

how to do a substitution on 5x-y=-13,-7x-3y=5

Answer 1

i know how to do this um i'm tired i'm sorry i think it's best for you to subtract the y's

Answer 2

i tried but the answer wont come out right

Answer 3

@holla! u can try to isolate the y in the first equation

Answer 4

http://www.youtube.com/watch?v=-fZLAYn9sGY this is the obvious answer 2 diss

Answer 5

well when I pluged it in it came to (-2,3) which is right I juz don't know how to solve it to get that answer

Answer 6

start with the first equation
5x-y=-13

add + y to both sides, like this
5x -y + y = -13 + y

on the left side, what does -y + y simplify to ?

Answer 7

so what are you cheating on?

Answer 8

well iv been trying to do this equation for quit awhile and I cant seem to get the answer to come out to (-2,3)

Answer 9

let me guess you just made this today

Answer 10

ur account

Answer 11

yes

Answer 12

help /_\

Answer 13

add + y to both sides, like this
5x -y + y = -13 + y

on the left side, what does -y + y simplify to ?

Answer 14

what is 1 y take away 1 y ?

Answer 15

o so okY THIS IS WHAT I PUT NOW 5x=-13+y

Answer 16

now add +13 to both sides of
5x=-13+y

5x+13= -13+13+y
simplify the right side

Answer 17

you should get
5x+13 = y
or (the same thing)
y= 5x+13

think of this as y is "short-hand" for (5x+13)

use the "long version" of y in
the second equation
-7x-3y=5

that means erase the y, and put (5x+13) in its place. can you do that ?

Answer 18

I got it now! got the answer thanks!:)