Question

x(x+1)(x+2)(x+3)=1680怎么解

Answer 1

x(x+1)(x+2)(x+3)=1680

[x(x+3)][(x+1)(x+2)]=1680

(x²+3x)(x²+3x+2)=1680

(x²+3x)²+2(x²+3x)-1680=0

(x²+3x+42)(x²+3x-40)=0

(x²+3x+42)(x+8)(x-5)=0(x²+3x+42>0)

(x+8)(x-5)=0

x=-8或x=5