LET’S TRY ONE
Differentiate f(x) = 3x4.
12x3
The power rule gives 3 × 4 × x3 = 12x3.
Learning steps & teaching tips
Use the power rule on a constant times a positive integer power.
- Multiply the coefficient by the exponent, then subtract one from the exponent.
- Work through the example. Explain how its evidence supports the answer.
- Try a new question; use the explanation to check your thinking.
Try it together
Write or draw your own example with different numbers. Solve it, then ask a partner to check the method as well as the answer.
Multiply the coefficient by the exponent, then subtract one from the exponent.