AlgebraEasy–MediumSum of a linear function's values at opposite inputs
Algebra practice question
The function f is defined by f(x) = 2.5x − 4. What is the value of f(2) + f(−2)?
Answer: -8
f(2) = 1 and f(−2) = −9, so the sum is −8. (In general f(a) + f(−a) = 2 × (−4).)
Common wrong answers
- If you answered 0
- 0 forgets the constant −4 in both values.
- If you answered 10
- 10 is f(2) − f(−2).
- If you answered -4
- −4 counts the constant once.
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