Question

用因式分解解方程(x的4次方)-(x的3次方)-7(x的2次方)+x+6=0

Answer 1

x^4-x^3-7x^2+x+6=0x^3(x-1)-(7x+6)(x-1)=0(x-1)(x^3-7x-6)=0(x-1)(x^3+x^2-x^2-x-6x-6)=0(x-1)[x^2(x+1)-x(x+1)-6(x+1)]=0(x-1)(x+1)(x^2-x-6)=0(x-1)(x+1)(x-3)(x+2)=0x=1或x=-1或x=3或x=-2