Well, that's going to be acceleration as a function of time. So they give us velocity, so from velocity we can figure out acceleration. So let me just rewrite that. So we know that v of t is equal to negative t to the third power plus six t squared plus two t, and so from that we can figure out the acceleration as a function of time, which is just going to be the derivative with respect to t of the velocity. So I'll just use the power rule a bunch. So that's going to be, this is a third power right there, so negative three t squared plus two times six is 12 t to the first plus two, so that's our acceleration as a function of time. And we want to figure out when we obtain our maximum acceleration.