Х(х+y)^2-y(x-y)^2+2y(x^2+y^2) и решить при х=2,5 , у=0,5

х(х+y)²-y(x-y)²+2y(x²+y²)=x(x²+2xy+y²)-y(x²-2xy+y²)+2x²y+2y³=
=x³+2x²y+xy²-x²y+2xy²-y³+2x²y+2y³=x³+3x²y+3xy²+y³=(x+y)³
(x+y)³ при х=2,5 , у=0,5
(2,5+0,5)³=3³=27