AlgebraEasy–MediumWhere a decreasing linear function reaches zero
Algebra practice question
A linear function f has f(1) = 10, and f decreases by 4 for each increase of 1 in x. For what value of x is f(x) = 0?
Answer: 3.5 or 7/2
f(x) = 10 − 4(x − 1) = 14 − 4x, which is 0 when x = 3.5.
Common wrong answers
- If you answered 3
- 3 gives f(3) = 2, not 0.
- If you answered 4
- 4 gives f(4) = −2.
- If you answered 2.5
- 2.5 counts 10 ÷ 4 steps from x = 0 instead of from x = 1.
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