1.(x+y)²-9x-9y-10=x²-9y+81/4+y²-49/y=(x-9/2)²+(y-7/4)²
2.x²+2(m-1)x+m²-2m-3=0
x²+2mx-2x+m²-2m-3
(x+m)²-2(x+m)+1-4=0
(x+m-1)²-4=0
3.化简=-2ab=1
4.a²+2a+b²-6b+10=0
a²+2a+1+b²-6b+9=0
(a+1)²+(b-3)²=0
所以,a=-1,b=3
5.(x+1)(x-1+8)>(x+5)(x+1)
x²-6x+7>x²+6x+5
-6x>6x
-x>x
x小于0
6.a²+b²+c²=ab+bc+ac
2a²+2b²+2c²-2ab-2bc-2ac=0
(a-b)²+(b-c)²+(c-a)²=0
所以a=b=c,三角形为等边三角形