（4X^2-4X-35）(X^2-9)-91
=(2x-7)(2x+5)(x+3)(x-3)-91
=[(2x-7)(x+3)][(2x+5)(x-3)]-91
=(2x²-x-21)(2x²-x-15)-91
=(2x²-x)²-36(2x²-x)+224
=(2x²-x-28)(2x²-x-8)
=(2x+7)(x-4)(2x²-x-8)
（4X^2-4X-35）(X^2-9)-91分解因式
（4X^2-4X-35）(X^2-9)-91
=(2x-7)(2x+5)(x+3)(x-3)-91
=[(2x-7)(x+3)][(2x+5)(x-3)]-91
=(2x²-x-21)(2x²-x-15)-91
=(2x²-x)²-36(2x²-x)+224
=(2x²-x-28)(2x²-x-8)
=(2x+7)(x-4)(2x²-x-8)