Question

求函数y=9x∧3-lnx的极值和单调区间

Answer 1

求导,f'(x)=27x^2-1/x=(27x^3-1)/x

x=1/3时,f'(x)=o,则极小值f(1/3)=1/3-ln(1/3),x在(0,1/3)递减,在 [1/3,无穷大）递增