I think if you look at Taylor's Theorem, you'll find that the error in the linear approximation is and the error in the quadratic approximation is . Otherwise it sounds like you have the right idea.

You'll have to give the actual Taylor expansion (5 + (number)h + (number)h^2) - that's what "Give the quadratic approx." means. You probably know that, but it wasn't clear from your post.

- Hollywood