Let $f ( x ) = 6 x ^ { 5 } - 90 \ln x$

Multiple Choice

Let $f ( x ) = 6 x ^ { 5 } - 90 \ln x$ , for x > 0. Find the minimum value of f for x > 0.

A) 0
B) $3 \left( 3 ^ { 5 } - 15 \ln 3 \right)$
C) 18(1 - ln 3)
D) $6 \left( 3 ^ { 5 } - 15 \ln 3 \right)$