Mathematics

Problem

A particle moves along a straight line so that its displacement after

t

seconds is

s(t)=3t^2-12t+7

in metres. Find its velocity at

t=3\,\text{s}

. a)

18\,\text{m/s}

6\,\text{m/s}

-6\,\text{m/s}

13\,\text{m/s}