SOLUTION: pls help me to solve this equation by substitution. 1.-3x+3y=4 -x-2y=11 2.-3x-4y=2 3x+3y=-3 3.-5x-8y=17 2x-7y=-17

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: pls help me to solve this equation by substitution. 1.-3x+3y=4 -x-2y=11 2.-3x-4y=2 3x+3y=-3 3.-5x-8y=17 2x-7y=-17      Log On


   

Question 325290: pls help me to solve this equation by substitution.
1.-3x+3y=4
-x-2y=11
2.-3x-4y=2
3x+3y=-3
3.-5x-8y=17
2x-7y=-17
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
I'll do the first one to get you started. You should post one problem at a time.

# 1

-x-2y=11+ Start with the second equation.


-x=2y%2B11+ Add 2y to both sides.


x=-2y-11+ Multiply every term by -1


-3x%2B3y=4 Go to the first equation.


-3%28-2y-11%29%2B3y=4 Plug in x=-2y-11+


6y%2B33%2B3y=4 Distribute.


9y%2B33=4 Combine like terms on the left side.


9y=4-33 Subtract 33 from both sides.


9y=-29 Combine like terms on the right side.


y=-29%2F9 Divide both sides by 9 to isolate y.


x=-2y-11+ Go back to the previously isolated equation.


x=-2%28-29%2F9%29-11+ Plug in y=-29%2F9


x=58%2F9-11+ Multiply


x=-41%2F9+ Subtract.


So the solutions are x=-41%2F9+ and y=-29%2F9 which form the ordered pair