1+х^2-2х=(х-1)^2
(2х-1)(2х+1)=4х^2-1
(к+0.5)^2=к^2+к+0.25
28ху+49х^2+4у^2=(2у+7х)^2
(7х-2)(7х+2)=49х^2-4
(-а-1)^2=а^2+2а+1
(б+3)^2=б^2+6б+9
25б^2+10б+1=(5б+1)^2
(2а-3б)(2а+3б)=4а^2+9б^2
б^2-4/9=(б-2/3)(б+2/3)
(10-с)^2=100-20с+с^2
81а^2-18аб+б^2=(9а-б)^2
(5х^2+2у^3)(5х^2-2у^3)=25х^4-4у^6
-49а^2+16б^2=(4б-7а)(4б+7а)
(-б-3)^2=б^2+6б+9
(0.3-м)^2=0.09-0.6м+м^2
8аб+б^2+16а^2=(4а+б)^2
(4+у^2)(у^2-4)=у^4-16
(у+9)^2=у^2+18у+81