解
x²+4x³-4-16x
=(4x³+x²)-(16x+4)
=x²(4x+1)-4(4x+1)
=(x²-4)(4x+1)
=(x-2)(x+2)(4x+1)a^2-4a-4b^2+4=???解a²-4a-4b²+4=(a²-4a+4)-4b²=(a-2)²-(2b)²=(a-2+2b)(a-2-2b)=(a+2b-2)(a-2b-2)