Advanced MathMediumSmaller of two numbers from a difference and a product
Advanced Math practice question
Two positive numbers differ by 5, and their product is 84. What is the smaller of the two numbers?
Answer: 7
If the smaller number is n, then n(n + 5) = 84, so n² + 5n − 84 = 0 and (n + 12)(n − 7) = 0. The positive solution is n = 7.
Common wrong answers
- If you answered 12
- 12 is the larger number.
- If you answered -12
- −12 is the rejected negative root.
- If you answered 16.8
- 16.8 divides 84 by 5.
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