Question

( X+ y )^2 - ( x-y )^2 решите пожалуйста

Answer 1

x^2+2xy+y^2-x^2+2xy-y^2=4xy

Answer 2

(x+y)²-(x-y)²=(x²+2xy+y²)-(x²-2xy+y²)=x²+2xy+y²-x²+2xy-y²=2xy+2xy=4xy