48а∧6b-243a²b²=3a²b(16a∧4-81b)
(a+1(a+2)-(a+1)(a-2)-a-1=a²+3a+2-a²+a+2-a-1=4a-3
x²y²-z²t²+x²z²-y²t²=(x²y²-y²t²)+(x²z²-z²t²)=у²(х²-t²)-y²(x²-t²)=(y²-y²)(x²-t²)=(x-t)(x+t)
(a²-b²)(a-c)-(a²-c²)(a+b)=(a-b)(a+b)(a-c)-(a+c)(a-c)(a+b)
(x+2y)² -9y²=x²+4y+4y²-9y²=x²-1=(x-1)(x+1)