Question:
x - y = 4, x² + y² =10 ആയാൽ x + y എത്ര?
A2
B3
C4
D5
Answer:
A. 2
Explanation:
(x + y)² + (x - y)² = x² + 2xy +y² + x² - 2xy + y² = 2(x² + y²) (x+ y)² = 2(x² + y²) - (x - y)² = 2 × 10 - 16 = 20 - 16 = 4 ( x + y) = 2
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Question:
A2
B3
C4
D5
Answer:
(x + y)² + (x - y)² = x² + 2xy +y² + x² - 2xy + y² = 2(x² + y²) (x+ y)² = 2(x² + y²) - (x - y)² = 2 × 10 - 16 = 20 - 16 = 4 ( x + y) = 2
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