X³-y³=(x-y)(x²+xy+y²)
x³-y³-5x(x²+xy+y²)
=(x-y)(x²+xy+y²)-5x(x²+xy+y²)=
=(x²+xy+y²)(x-y-5x)=
=(x²+xy+y²)(-y-4x)=
=-((x²+xy+y²)(4x+y)
1)(a-5b)^2(a+5b)^2=((a-5b)(a+5b))^2=(a^2-25b^2)^2=a^4-50a^2b^2+625^4
2)a^2-12a+36=(a-6)^2; при a=506
(a-6)^2=(506-6)^2=(500)^2=250000
5-Х и подели все это на 2
((5-Х)/2)