Hi again, all! I worked out the velocity of this curve s= t^2 - 8t + 18 at t = 4 to be 2 m/s, but the graph on my calculator really doesn't look like the instant v at t = 4 is anywhere near 2 (looks like zero). So I tried to write out the general formula for this and am not sure my next step, any hint would be valued

lim h -> 0 (a^2 + 2ah + h^2 - 8a - 8h + 18) / h

There's nothing to cancel out so how can I make this into a workable limit?