help please exam tommarrow =(

i dont get it i listened to teacher but i can't get how to do elimination properly can some1 give me an example of how to do i would really appreciate it.

heres one:

for y

-x+5y=7
+
3x-2y=-6
----------
times 3

-3x+15y=21
+
3x-2y=-6
-----------
0x+13y=15

13y/13=15/13

y= 15/13

For X

-x+5(15/13)=7
-x+75/13=7
-x = 7-75/13
-x = 91-75/13
-x = 16/13
x = -16/13

Is that right...im not to sure

[Robert Fogt]

You've lost me a bit, adding formulas together doesn't sound right, solve for each one.

-x + 5y = 7
(add x to each side)
5y = 7 + x
(subtract 7 from each side)
x = 5y - 7

Next one
3x-2y=-6
(add 2y to each side)
3x = 2y - 6
(divide each side by 3)
x = 2/3y - 2

and so on.... Or did I completely misunderstand your problem?

You did it right.

Professor Robie.