初二数学题

显示全部楼层 · 2008-12-21 19:34:51

1.x^2+12x+36
2.a^2+2a+1
3.16x^2+24x+9
4.-x^2+4xy-y^2
5.(a+b)^2-12(a+b)+36
6.867^2-567^2
7.若a^2+b^2-6a-4b+13=0,求3a+2b的值
8.已知x^2y^2+x^2+y^2+1=4xy,求xy(x-y)的值

千问 · 2008-12-21 19:34:51

1.x^2+12x+36 =x^2+2*x*6+6^2=(x+6)^22.a^2+2a+1 =(a+1)^23.16x^2+24x+9 =(4x)^2+2*(4x)*3+3^2=(4x+3)^24.-x^2+4xy-y^2 =-(x^2-4xy+y^2)5.(a+b)^2-12(a+b)+36 =(a+b)^2-2*(a+b)*6+6^2=(a+b-6)^26.867^2-567^2 =(867+567)*(867-567)=1434*300=4302007.a^2+b^2-6a-4b+13=0(a^2-6a+9)+(b^2-4b+4...

千问 · 2008-12-21 19:34:51

1.x^2+12x+36=(x+6)^22.a^2+2a+1=(a+1)^2 3.16x^2+24x+9=(4x+3)^2 4.-x^2+4xy-y^2=-(x+y)^2-6xy 5.(a+b)^2-12(a+b)+36=(a+b-6)^2 6.867^2-567^2=(867+567)(867-567)=1434*300=430200...

千问 · 2008-12-21 19:34:51

a^2+b^2-6a-4b+13=0(a-3)^2+(b-2)^2=0a=3 b=23a+2b=13x^2y^2+x^2+y^2+1=4xyx^2y^2+x^2+y^2+1-4xy=0(xy-1)^2+(x-y)^2=0x=yxy(x-y)=0...