1.a²+2a+b²-6b+10=0
(a²+2a+1)+(b²-6b+9)-1-9+10=0
(a+1)²+(b-3)²=0
(a+1)²≥0
(b-3)²≥0
∴a=-1 b=3
2.已知平行四边形的面积为4a²＋4a+1,一边长为2a+1,则这边上的高为：
(4a²＋4a+1)/(2a+1)
=(2a+1)²/(2a+1)
=2a+1
3.(m²+4n²)/2 -2mn =（(m-2n)²+4mn）/2-2mn
=(m-2n)²/2+2mn-2mn
=(m-2n)²/2
=（2n-m)²/2
=2