Question

Please help me with my homework, I don't know how to do this.

Solve the system using elimination, make sure to show work.

5x + 4y = 12
3x – 3y = 18

Answer 1

Notice \[
4y\\
-3y
\]

Answer 2

You want them to cancel. so to do that you would multiply the top by 3 and the bottom by 4.

Answer 3

that would make them \[
12y\\
-12y
\]

Answer 4

what?

Answer 5

Since \(12y-12y=0\)

Answer 6

15x +12y = 36
12x -12y = 72
is this right so far

Answer 7

Yes

Answer 8

Now add both equations.

Answer 9

27x = 108
x = 108/27 = 4

Answer 10

15*4+12y=36
y=-2

Answer 11

x is 4 and y is -2 right

Answer 12

http://www.wolframalpha.com/input/?i=5x+%2B+4y+%3D+12%2C+3x+%E2%80%93+3y+%3D+18

Answer 13

The best way to check your work is to plug them into the original equations and see if they're true.

Answer 14

thanks :D