第1个回答 2011-06-21
1、=-(12xy+x^2+36y^2)
=-(x+6y)^2
2、=a(a^2-8a+16)
=a(a-4)^2
3、=( x^2-2xy+y^2)-9
=(x-y)^2-9
=(x-y+3)(x-y-3)
4、=a^2(x-y)-b^2(x-y)
=(x-y)(a^2-b^2)
=(x-y)(a+b)(a-b)
(a+2b-c)(a-2b+c)
=[a+(2b-c)][a-(2b-c)]
= a^2-(2b-c)^2
=a^2-4b^2+4bc-c^2
(a+b-c)^2
=[(a+b)-c]^2
=(a+b)^2-2c(a+b)+c^2
=a^2+2ab+b^2-2ac-2bc+c^2
这都是公式啊,孩子
第2个回答 2011-06-21
1. -(x+6y)^2
2. a(a+4)^2
3. (x-y+3)(x+y-3)
4. (x-y)(a+b)(a-b)
计算1 = a^2 - (2b-c)^2 = a^2 - 4b^2 -c^2 +4bc
计算2 = a^2 + b^2 + c^2 + 2ab - 2ac - 2bc
第3个回答 2011-06-21
(a+b-c)^2
={(a+b)-c}^2
=(a+b)^2-2c(a+b)+c^2
=a^2+2ab+b^2-2ac-2bc+c^2
(a+2b-c)(a-2b+c)
=[a+(2b-c)][a-(2b-c)]
=a^2-(2b-c)^2
=a^2-4b^2+4bc-c^2
-12xy-x^2-36y^2
=-(x+6)^2
只知道这几个其它的忘了
第4个回答 2011-06-21
1 -12xy-x^2-36y^2=-(x^2+12xy+36y^2)=-(x+6y)^2
2 a^3-8a^2+16a=a(a^2-8a+16)=a(a-4)^2
3 x^2-2xy+y^2-9=(x-y)^2-9=(x-y+3)(x-y-3)
4 a^2(x-y)+b^2(y-x)=(x-y)(a^2-b^2)=(x-y)(a-b)(a+b)
1(a+2b-c)(a-2b+c) =[a+(2b-c)][a-(2b-c)]=a^2-(2b-c)^2=a^2-4b^2+4bc-c^2
2 (a+b-c)^2=(a+b)^2-2c(a+b)+c^2=a^2+2ab+b^2-2ac-2bc+c^2本回答被提问者采纳
第5个回答 2011-06-21
1 -(x+6y)^2
2 a(a^2-8a+16)=a(a-4)^2
3 (x-y)^2-9=(x-y-3)(x-y+3)
4 a^2(x-y)-b^2(x-y)=(a^2-b^2)(x-y)=(a-b)(a+b)(x-y)