Two questions that are giving me trouble; could someone please show me how?

Question One

A mushroom was observed while growing, and all linear dimensions were growing proportionately. Therefore, the volume increased according to the formula $\displaystyle V=cL^3$ WhereLis any linear dimension andcis a constant. Show that

$\displaystyle

\frac{1} {V}\left[\frac{dv} {dt}\right] = 3 \frac{1}{L}\left[\frac{dL}{dt}\right]

$

Using differentials find the percentage error ingislis measured accurately butThas an error of 1%

Question TwoThe acceleration due to gravity

gcan be determined by measuring the period of swing of a pendulum. If the length of the pendulum island the measured period isT, thengis given by the formula

$\displaystyle g = \frac{4 (pi)^2l} {T^2}$