.1(m+n)^2-4m(m+n)+4m^2
=(m+n-2m)^2
=(n-m)^2
2 (a-b)^2+4ab
=a^2+b^2+2ab
=(a+b)^2
3 4xy^2-4x^2 y-y^3
=-y(-4xy+4x^2+y^2)
=-y(2x-y)^2
4 4y^2+my+9
=(2y)^2+my+3^2
m=2x3x2=12 或者-12
1.(m+n)^2-4m(m+n)+4m^2=[(m+n)-2m]^2=(n-m)^2
2. (a-b)^2+4ab=a^2-2ab+b^2+4ab=a^2+2ab+b^2=(a+b)^2
3. 4xy^2-4x^2 y-y^3=-y*(4x^2-4xy+y^2)=-y*(2x-y)^2
9.已知4y^2+my+9是完全平方式,求m的值。【写过程】
4y^2+my+9=(2y)^2+2*(m/2)*y+3^2, 若其为完全平方式,则m/2=正负3,∴m=6或者-6
(m+n)^2-4m(m+n)+4m^2=m^2+n^2-4m^2-4mn+4m^2=m^2+n^2-4mn=(m-n)^2