Advanced MathEasy–MediumPositive number from a square minus a multiple
Advanced Math practice question
The square of a positive number, minus twice the number, equals 15. What is the number?
Answer: 5
n² − 2n − 15 = (n − 5)(n + 3) = 0, so n = 5.
Common wrong answers
- If you answered 3
- 3 gives 9 − 6 = 3.
- If you answered 15
- 15 copies the constant.
- If you answered -3
- −3 is the negative root.
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