1）x²-y²-9z²+6yz 2）2x³-x²-2x+1

1)ԭʽ=x²-(y²-6yz+9z²) = x²-(y-3z)² =[x+(y-3z)][x-(y-3z)] 2ԭʽ=x²-1)(2x+1) ûʲôд 3ԭʽ=a²-(4b²-12bc+9c² ) =a²-(2b-3c)² =[a+(2b+3c)][a-(2b+3c)] 4ԭʽ=a^4-(x²-4ax+4a² ) =a^4-(x-2a)² =[a²+(x-2a)][a²-(x-2a)] ȫѭa²-b²=(a+b)(a-b)