Advanced MathHardSum of two numbers from their product and the sum of their squares
Advanced Math practice question
The product of two positive numbers is 36, and the sum of their squares is 97. What is the sum of the two numbers?
Answer: 13
(a + b)² = a² + b² + 2ab = 97 + 72 = 169, so a + b = 13 (positive numbers). The numbers are 9 and 4.
Common wrong answers
- If you answered 5
- 5 is a − b, from (a − b)² = 97 − 72 = 25.
- If you answered 133
- 133 adds ab once instead of twice.
- If you answered 169
- 169 is (a + b)², not a + b.
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