Advanced MathMediumDistance between a parabola's x-intercepts
Advanced Math practice question
The function f is defined by f(x) = x² − 2x − 15. The graph of f crosses the x-axis at two points. What is the distance between those two points?
Answer: 8
x² − 2x − 15 = (x − 5)(x + 3), so the intercepts are 5 and −3, which are 8 apart.
Common wrong answers
- If you answered 2
- 2 is the sum of the intercepts.
- If you answered 15
- 15 is the size of the constant term.
- If you answered -15
- −15 is the product of the intercepts.
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