#### Problem 17E

17. The mass of the part of a metal rod that lies between its left end and a point $x$ meters to the right is $3 x^{2} \mathrm{~kg} .$ Find the linear density (see Example 2) when $x$ is (a) $1 \mathrm{~m}$, (b) $2 \mathrm{~m}$, and

(c) $3 \mathrm{~m}$. Where is the density the highest? The lowest?