分解因式，写清步骤。

显示全部楼层 · 2008-12-26 16:46:45

（2x+y)^2-(x+2y)^2
12x^2-3y^2
(m+n)^2-4m(m+n)+4m^2
a^2+2a(b+c)+(b+c)^2
拜托，一定要写清步骤，谢谢了。
还有这道m^2-14m+49
（a-b)^2+4ab
(p-4)(p+1)+3p
4xy^2-4x^2y-y^3
3ax^2-3ay^2

千问 · 2008-12-26 16:46:45

1、（2X+Y)^2-(X+2Y)^2=4X^2+4XY+Y^2-X^2-4XY-4Y^2=3X^2-3Y^2=3(X^2-Y^2)=3(X+Y)(X-Y) 2、12x^2-3y^2=(2根3*X)^2-(根3*Y)^2=(2根3*X+根3*Y)(2根3*X-根3*Y) 3、(m+n)^2-4m(m+n)+4m^2=m^2+2mn+n^2-4m^2-4mn+4m^2=m^2-2mn+n^2=(m-n)^2 4、a^2+2a(b+c)+(b+c)^2=a^2+2ab+2ac+b^2+2bc+c^2=(a+b+c)^2 5、m^2-14m+49=m^2-14m+7^2=(m-7)^2 应该是对的吧,给我一点分吧...

千问 · 2008-12-26 16:46:45

（2x+y)^2-(x+2y)^2 =[(2x+y) + (x+2y)][(2x+y) - (x-2y)] = 3(x+y)(x-y)12x^2-3y^2 =3(4x^2 - y^2)=3(2x-y)(2x+y)(m+n)^2-4m(m+n)+4m^2 =[(m+n) -2m)]^2 = (n-m)^2a^2+2a(b+c)+(b+c)^2 ...

千问 · 2008-12-26 16:46:45

1、（2X+Y)^2-(X+2Y)^2=4X^2+4XY+Y^2-X^2-4XY-4Y^2=3X^2-3Y^2=3(X^2-Y^2)=3(X+Y)(X-Y)2、12x^2-3y^2=(2根3*X)^2-(根3*Y)^2=(2根3*X+根3*Y)(2根3*X-根3*Y)3、(m+n)^2-4m(m+n)+4m^2=m^2+2mn+n^2-4m^2-4m...