Question

Докажите тождетво:
(а+1)в кубе -(а+1)=а(а+1)(а+2)

Answer 1

a^3+3a^2+3a+1-a-1=a(a+1)(a+2)
a^3+3a^2+2a=a(a+1)(a+2)
a(a^2+3a+2)=a(a+1)(a+2)
D=1   a=-3±1/2      a1=-1, a2=-2
a(a+1)(a+2)=a(a+1)(a+2)