AlgebraEasyInput that gives a stated output
Algebra practice question
The function f is defined by f(x) = 4x − 3. For what value of x is f(x) = 9?
Answer: 3
Set 4x − 3 = 9: 4x = 12, so x = 3.
Common wrong answers
- If you answered 12
- 12 is 4x, one step short; divide by 4.
- If you answered 33
- 33 is f(9) = 36 − 3 — the OUTPUT at x = 9, not the input that gives 9.
- If you answered 1.5
- 1.5 comes from 4x = 6, subtracting 3 from 9 instead of adding it.
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