7年级数学题44

3a^3-12a^2+12a
=3a(a^2-4a+4)
=3a(a-2)^2

-9-6ab-a^2b^2
=-[(ab)^2+2*(ab)*3+3^2]
=-(ab+3)^2

1/4m^3n-1/4m^2n^2+1/16mn^3
=(1/16)mn(4m^2-4mn+n^2)
=(1/16)mn(2m-n)^2

a^4-2a^2+1
=(a^2-1)^2
=(a+1)^2(a-1)^2

（x-2y)^2-12（x-2y)+36
=(x-2y)^2-2*(x-2y)*6+6^2
=(x-2y-6)^2

(a+2b)^2+2（a+2b)(2a+b)+(2a+b)^2
=[(a+2b)+(2a+b)]^2
=(3a+3b)^2
=[3(a+b)]^2
=3^2*(a+b)^2
=9(a+b)^2

1)3a的3方-12a的2方+12a=a(3a的2方-12a+12)=a(3a-6)(a-2)

2)-9-6ab-a的2方b的2方=-(9+6ab+a的2方b的2方)=-(a的2方b的2方+6ab+9)=-(ab+3)的2方

3)1/4m的3方n-1/4m的2方n的2方+1/16mn的3方=1/16mn(4m的2方-4mn+n的2方)=1/16mn(2m-n)的2方

4)a的4方-2a的2方+1=(a的2方-1)的2方

5)(x-2y)的2方-12（x-2y)+36= [(X-2Y)-6]的2方

6)(a+2b)的2方+2（a+2b)(2a+b)+(2a+b)的2方=[(a+2b)+(2a+b)]的2方