(4x+y)^2
answer:16x^2+y^2
is this correct?
not quite
(4x+y)(4x+y) = 16x^2 + 4xy + 4xy + y^2
= 16x^2 + 8xy + y^2
You can always check your results by evaluating with numbers. For example, if x=1 and y=2,
(4+2)^2 = 36
16*4+1 = 65
a good sign your result is wrong