16Hit1600
Advanced MathHardSum of the squares of two numbers from their sum and product

Advanced Math practice question

The sum of two numbers is 8 and their product is 13. What is the sum of the squares of the two numbers?

Answer: 38

x² + y² = (x + y)² − 2xy = 64 − 26 = 38.

Common wrong answers

If you answered 51
51 subtracts xy once instead of twice.
If you answered 64
64 is (x + y)², forgetting to subtract 2xy.
If you answered 90
90 adds 2xy instead of subtracting.

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