Expert: Abe Mantell - 1/14/2008

Question
i dont understand the elimination method at all..
i need help big time.!

2x-y=2
3x+4y=25

Answer
Hello Elizabeth,

The elimination method requires that we multiply one or
both equations by a non-zero number so that when we add
the two equations together, one of the variables gets
"eliminated" (i.e. drops out).  In your case, I'd
multiply the first equation by 4, to get: 8x-4y=8, so
that when we add it to the second equation, the y's
get "eliminated."  So...
8x-4y=8
+3x+4y=25
=========
11x = 33, now divide by 11 to get
x=3...now substitute x=3 into one of the two original
equations to determine y.  I'll use the first equation...
2(3)-y=2 ==> 6-y=2 ==> -y=-4 ==> y=4

So, x=3, y=4.

OK?  Abe