1.ab-2a-2b+4
=a（b-2）-2(b-2)
=(a-2)(b-2)
2.x³+6x²+11x+6
=x³+6x²+9x+2x+6
=x(x²+6x+9)+2(x+3)
=x(x+3)²+2(x+3)
=(x+3)(x²+3x+2)
=(x+1)(x+2)(x+3)