The problem is:

"The points A and B have coordinates $\displaystyle (a,a^2)$ and $\displaystyle (2b,4b^2)$ respectively. Determine the gradient of AB in it's simplest form."

The equation for gradient that we use is$\displaystyle m=y^2-y^1 / x^2-x^1$

So this is what I've got so far

$\displaystyle m=y^2-y^1 / x^2-x^1$

$\displaystyle m=4b^2-a^2 / 2b-a$

Can someone please show me how to work through it?

Thanks.