Enjoy the flight....
.... And, learn something new...
At what point is the tangent to f(x) = x^2 + 4x + 1 a horizontal line?
Rate of change & Tangent Lines - Lesson, examples, and illustrations from Paul's Online Math Notes
Using the definition of derivative practice problems at mathwarehouse.com
Instantaneous Rate of Change Formula
"Change yourself" from Spiked Math (#442)