Question

Simplifying of $(x+y{)}^2-(x-y{)}^2$

Answer 1

Applying the identities in ${\left(x+y\right)}^2-{\left(x-y\right)}^2$

${\left(x+y\right)}^2-{\left(x-y\right)}^2=\left(x^2+y^2+2xy\right)-\left(x^2+y^2-2xy\right)$

$=x^2+y^2+2xy-x^2-y^2+2xy$

$=4xy$