x(x-1)(x+1)x^3-x-120=0(x-125)-x+5=0(x-5)(x^2+5x+25)-(x-5)=0(x-5)(x^2+5x+24)=0x^2+5x+24=0无实数解所以x=5
120=4×5×6所以x=5
(x-1)*x*(x+1)=120=4*5*6所以x=5
