Question

Daca x×y=5 si xy=6 atunci x la a 2+y la a 2 =?

Answer 1

x + y = 5   si   x y = 6

x² + y² = ?

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( x + y )² = x² + 2 x y + y²

x² + y² = ( x + y )² - 2 x y = 5² - 2 × 6 = 25 - 12 = 13