(2+х)²=
(4х-1)²=
(2х+3у)²=
(х²-5)²=
(5х+2)²-20х=

(2+x)²=4+4x+x²(4x-1)²=16x²+8x-1(2x+3y)²=4x²+6xy+9y²(x²-5)²=x⁴+10x-25(5x+2)²-20x=25x²+20x+4-20x=25x²+4