函数y=9x+4/(x-1) , (x>1)的最小值是?

问题描述:

函数y=9x+4/(x-1) , (x>1)的最小值是?

y=9x+4/(x-1)
=9(x-1)+4/(x-1)+9 (x-1>0)
>=2√9(x-1)[4/(x-1)]+9
=12+9
=21
函数最小值为21