Before the midterm
Applying the power rule to an exponential
The habit: xn brings the n down, but ax has the variable upstairs and differentiates to ax log a.
8 practice questions are built to catch it, in 3 topics.
See it fail in a figure: Not the power rule, in the exponential and trigonometric functions lesson
What it looks like
A question from exponential and trigonometric functions, with the answer this slip gives beside the right one.
Which of the following is the derivative of ?
- With the slip
- Worked through
x · 3x−1 treats the x in 3x as a fixed exponent. Here the base 3 is fixed and x varies: write 3x = ex log 3 and use the chain rule.
Where it comes up
- The definition of the derivative2 questions
- Exponential and trigonometric functions5 questions
- The chain rule and logarithms1 question
Practise against it
Each of these has an answer this slip gives. Work them on paper: if you fall into it, the verdict names it and the question comes back in review.
- 01Which of the following is the derivative of ?
Exponential and trigonometric functionsIntroductory
- 02Let for . Find .
Exponential and trigonometric functionsIntroductory
- 03For a base , the slope of at is the limit below.
The definition of the derivativeStandard
- 04Use to evaluate the limit below.
The definition of the derivativeStandard
- 05A bacterial culture contains cells hours after it is started. How fast is the culture growing at ?
Exponential and trigonometric functionsStandard
- 06From the definition of the derivative, for every base , where . A calculator estimates . Without estimating another limit, find the slope of at .
Exponential and trigonometric functionsStandard