Worked examples
Two examples
Example 1
If f(x) = 3x − 5, for what x is f(x) = 16?
- Set the rule equal to the output: 3x − 5 = 16.
- Add 5: 3x = 21. Divide by 3.
Answer: x = 7
Example 2
If f(x) = −2x + 4, for what x is f(x) = 10?
- −2x + 4 = 10, so −2x = 6.
- x = −3. Check: −2 × (−3) + 4 = 10.
Answer: x = −3
Where this is taught: Quiz 41: Functions, “What a function is”
The drill
Ten problems
How many:
Type each answer. Then press Check my answers at the bottom.Write each answer on the line. The answer key, with the reasoning, is on the last page.