y -x =2 and y + x= -2 ,Then ( x+y)(x-y)=?
We want the product of and
. We’re given that
, so we know we can plug in
there.
We need to be careful on the other part. We’re given that , and we need to use that to find the value of
. Let’s do it by multiplying each side by
:
There, so now we know that and
. Therefore,
.