Advanced MathHardSum of inputs sharing an output on a parabola
Advanced Math practice question
The function f is defined by f(x) = 2(x − 3)² − 5. If f(a) = f(b) = 3 and a ≠ b, what is the value of a + b?
Answer: 6
The parabola is symmetric about x = 3, so a and b are equally spaced around 3 and sum to 6.
Common wrong answers
- If you answered 1
- 1 is the smaller input alone.
- If you answered 3
- 3 is the axis of symmetry, half the sum.
- If you answered 5
- 5 is the larger input alone.
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