• July 19th 2008, 09:30 AM
stanton13
If z=2t^3 - 5t

what is the gradient of a graph of z against t at t = 3?

The answerneeds to be a number not in scientific notation

Thanks
• July 19th 2008, 09:48 AM
Simplicity
Quote:

Originally Posted by stanton13
If z=2t^3 - 5t

what is the gradient of a graph of z against t at t = 3?

The answerneeds to be a number not in scientific notation

A cubic curve will have a range of gradients. To find the gradient at a specific point, find the derivative and insert the value at which you want to find the gradient (In this case when $t=3$).
$z=2t^3 - 5t \therefore \frac{\mathrm{d}z}{\mathrm{d}t} = 6t^2 - 5$.
Inserting $t=3$ into the derivative will give you the gradient at that point.