AlgebraVery hardInput where one linear function is twice another
Algebra practice question
The functions f and g are defined by f(x) = 3x − 4 and g(x) = −2x + 11. For what value of x is f(x) equal to 2g(x)?
Answer: 26/7
3x − 4 = 2(−2x + 11) = −4x + 22 → 7x = 26 → x = 26/7.
Common wrong answers
- If you answered 3
- 3 is where f(x) = g(x), not 2g(x).
- If you answered 26
- 26 is 7x, before dividing.
- If you answered 18/7
- 18/7 comes from 3x − 4 = −4x + 14, halving the 22 instead of doubling the 11.
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