If f(x) = x² − 3x, what is f(−2)?
Answer in (no unit).
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10 (no unit)
Replace x with −2: (−2)² − 3(−2) = 4 + 6 = 10.
Reference: Function notation; evaluating with negative inputs
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Functions practice questions
27 questions from the electrical apprenticeship aptitude practice test.
Functions practice test
10 questions, graded as you go, with the reason for every answer. No sign-up.
What this covers
- Evaluating functions
- Slope and intercepts
- Tables and graphs
- Variation
Sample questions
If f(x) = 2x − 5, for what value of x does f(x) = 11?
Answer in (no unit).
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8 (no unit)
Set the rule equal to 11: 2x − 5 = 11. Add 5: 2x = 16. Divide by 2: x = 8. Check: f(8) = 16 − 5 = 11.
Reference: Function notation; finding the input for a given output
For which value of x is the function f(x) = 1/(x − 4) undefined?
- x = 1/4
- x = 0
- x = 4
- x = 1
Show the answer
C. x = 4
A fraction is undefined when its denominator is zero, and x − 4 = 0 when x = 4. At x = 0 the function is simply −1/4, which is a perfectly good value.
Reference: Domain of a rational function