I flipped open the cover when he gave the signal.
Twenty problems. Multiple choice for the first ten, free response for the last ten.
Find the derivative of f(x) = 3x² + 5x - 7.
Easy. Power rule. Bring down the exponent, multiply, reduce the power by one.
6x + 5.
Good. Next.
If f(x) = sin(2x), find f'(x).
Chain rule. The derivative of sin is cos, but you have to multiply by the derivative of the inside function.
2cos(2x).
Still with it. Next one.
Find the derivative of (x² + 1)(3x - 4) using the product rule.
Product rule. First times derivative of second, plus second times derivative of first.
Except I couldn't remember which was first and which was second.
Was it (x² + 1) · 3 + (3x - 4) · 2x?
Or was it backwards?
I stared at the problem.
The numbers didn't move like Cassidy said hers did. They just sat there, mocking me for not knowing something I'd done a hundred times before.
Breathe.
