Question

If (x - y)^2 = (x + y)^2 + a, what is a in terms of x and y?

Answer 1

\[a=(x-y)^2-(x+y)^2\] is a start

Answer 2

then multiply out and combine like terms on the right

Answer 3

when you are done you should get
\[a=-4xy\]

Answer 4

mmm

Answer 5

i got -2xy, but i think i found the error, thank you!