How do you solve #3x - y = 10# and #-x + y = -4#?

Question

4732 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-10-04T23:02:39

#(3,-1)#

You have to eliminate either the #x# or #y# variable.

This system is easier to solve if you eliminate the #y# variable then solve for x.

You can eliminate the #y# variable by adding the 2 equations together.

#3x-x# becomes #2x#

#-y+y# becomes #0# This is where #y# is eliminated.

#10-4# becomes #6#

You then left with ...

#2x=6#

Isolate x by dividing by #2#

#(cancel2x)/cancel2=6/2#

#x=6/2#

#x=3#

Now substitute the value of #x#, 3, into either of the original equations.

I will substitute into the first equation.

#3(3)-y=10#

#9-y=10#

Subtract #9# from both sides

#-y=10-9#

#-y=1#

Divide by #-1#

#(cancel(-1)y)/(cancel(-1))=1/-1#

#y=1/-1#

#y=-1#

The answer is #(3,-1)#