x的4次方减4乘x的3次方加4乘x的平方减1

x^4-4x³+4x²-1=(x^4-1)-4x³+4x²=(x²+1)(x²-1)-4x²(x-1)=(x²+1)(x+1)(x-1)-4x²(x-1)=(x-1)(x³+x²+x+1-4x²)=(x-1)[(x³-x²)-(2x²-x-1)]=(...