#### girlworld_club

##### Member

v = v = 6t^2 + 3t -2

or

a = v = 6t^2 + 3t -2

i know for velocity and acceleration, it is the derivitive equal to zero.

but how do we prove that these points are a maximum? do we differentiate again, after already differentiating and sub values of t in?

++ Another question.

For displacement:

if d2y/dx2 = -2cos(pi/x)

is 7/6 or 11/6 a maximum point. thanks again. and why?