a>b>0,求a^2+16/b*(a-b)的最小值
b*(a-b)≤[(b+a-b)/2]^2=a^2/4
a^2+16/b*(a-b)
≥a^2+64/a^2
≥16
取等号时a^2=64/a^2 b=a-b
a=2根号2 b=根号2