4x的四次方-13x+9
=4x^4-4x²+4x²-13x+9
=4x²(x²-1)+(4x-9)(x-1)
=4x²(x+1)(x-1)+(4x-9)(x-1)
=(x-1)(4x³+4x³+4x-9）不好意思，题目错了4x的四次方-13x的平方+9=(4x²-9)(x²-1)=(2x+3)(2x-3)(x+1)(x-1)