Railway Recruitment Board Mathematics — Question 657
Question
If x+y=10 and xy=21, find x²+y².
- 32
- 48
- 58
- 68
Correct answer
C — 58
Explanation (English)
x²+y² = (x+y)² - 2xy = 10² - 2(21) = 100 - 42 = 58
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