26/3848–12FE Reference Handbook 10.6 · Mathematics · p. 50 Derivatives, items 12 and 14

Handbook formula

Derivative of ln and e^u

p. 50 item 12 is d(ln u)/dx = (1/u) du/dx. Item 14 is d(e^u)/dx = e^u du/dx. Item 11 is log base a, not ln. ln u requires u > 0. The same page states that trigonometric arguments are in radians. The evaluations below are original.

Differentiable function of x
Natural log, u > 0
Exponential

Step-by-step solved example

Evaluate d(ln x)/dx at x = 4, and d(e^{2x})/dx at x = 0.

x = 4y = ln x, x > 0Replay
Tangent to ln x at x = 4 has slope 1/4. The curve is the logarithm, not a stress-strain test.
  1. 1. Natural log

    u = x, du/dx = 1, so d(ln x)/dx = 1/x. At x = 4 the slope is 1/4.

  2. 2. Exponential

    u = 2x, du/dx = 2, so d(e^{2x})/dx = 2 e^{2x}. At x = 0 this is 2(1) = 2.

Answer: 1/4 and 2

8 practice questions

0/8 correct

1.d(ln x)/dx at x = 4 is

2.d(e^{2x})/dx at x = 0 is

3.p. 50 item 12 is

4.p. 50 item 14 is

5.On the reals, ln x requires

6.d(ln(3x))/dx for x > 0 equals

7.Trigonometric derivatives on p. 50 use arguments in

8.d(e^x)/dx at x = 0 is