Advanced MathEasy–MediumNumber from its square plus itself
Advanced Math practice question
The square of a positive number, plus the number itself, is 42. What is the number?
Answer: 6
n² + n − 42 = (n + 7)(n − 6) = 0, so n = 6.
Common wrong answers
- If you answered 7
- 7 gives 49 + 7 = 56.
- If you answered 21
- 21 halves 42.
- If you answered -7
- −7 is the negative root.
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