第1个回答 2012-02-05
1、9(2x-y)^2-16(x+2y)^2=[3(2x-y)]^2-[4(x+2y)]^2=[3(2x-y)+4(x+2y)]*[3(2x-y)-4(x+2y)]=(10x+5y)(2x-11y)=5(2x+y)(2x-11y)
2、=[11(a-b)]^2-[13(a+b)]^2=[11(a-b)+13(a+b)][11(a-b)-13(a+b)]=-4(12a+b)(a+12b)
3、= n^2(m-2)+n(m-2)=(m-2)(n^2+n)=n*(n+1)(m+2)
4、=(x^2-2x)^2-4x+2x^2+1=(x^2-2x)^2+2(x^2-2x)+1=(x^2-2x+1)^2=[(x-1)^2]^2=(x-1)^4