(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