LET’S TRY ONE
If f(x) = 2x2 + 1, find f(−3).
19
2 × (−3)2 + 1 = 2 × 9 + 1 = 19.
Learning steps & teaching tips
Evaluate a squared-variable function at signed inputs.
- Square the entire signed input before multiplying by its coefficient.
- 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.
Square the entire signed input before multiplying by its coefficient.