2.阅读材料:若m
2-2mn+2n
2-8n+16=0,求m、n的值.
解:∵m
2-2mn+2n
2-8n+16=0,
∴(m
2-2mn+n
2)+(n
2-8n+16)=0,∴(m-n)
2+(n-4)
2=0,
∴(m-n)
2=0,(n-4)
2=0,∴n=4,m=4.
根据你的观察,探究下面的问题:
(1)已知x
2+2xy+2y
2+4y+4=0,求2x+y的值;
(2)已知△ABC的三边长a、b、c,且满足a
2+b
2-6a-8b+25=0,求△ABC的最大边c的范围;
(3)已知a-b=4,ab+c
2-6c+13=0,则a+b+c=
.