Originally Posted by

**MarcoMP** I'm not sure about this so a bit of help would be great.

Determine the average speed given that the distance travelled, $\displaystyle s$, in metres, relative to time, $\displaystyle t$, in seconds is $\displaystyle s(t)=2t^2 + 1$, between $\displaystyle t=2$ and $\displaystyle t=4$

Do I first do the first derivative of $\displaystyle s(t)=2t^2 + 1$ to get the equation for the speed at a point and then substitute in $\displaystyle t=2$ and $\displaystyle t=4$, and then use those values returned to get the gradient between the 2 points?