Question

Find the product:(x^2-2y)(x^2+2y)

Answer 1

\[x^4-4 y^2 \]

Answer 2

since
\[(a+b)(a-b)=a^2-b^2\]
therefore
\[(x^2-2y)(x^2+2y)=(x^2)^2-(2y)^2\]
\[x^4-4y^2\]