What is the simplified version of 3 square root 5c*square root 15c^3

The simplified version of 3√5c * √15c^3 is 3√(5*15)c^(1/2+3/2) which simplifies to 3√75c^2.5, which can be written as 3√75c^(5/2) or as 3√(75*c^2.5).