0 凹(2)t=3/a g(x)=x|x-t|它的凸区间是x>t,须包含[3,6]故a>1若a" property="og:description"/>
(1)f"(x)=6/x^3>0 凹
(2)t=3/a g(x)=x|x-t|它的凸区间是x>t,须包含[3,6]
故a>1
若a