Question

If X + Y is equal to 8 and X Y is equal to 15 then X square + 5 square is equal to blank

Answer 1

Hey mate !

Solution:

x + y = 8

xy = 15 => x = 15 / y

=> 15 / y + y = 8

=> 15 + y² / y = 8

=> y² + 15 = 8y

=> y² - 8y + 15 = 0

=> y² - 5y - 3y + 15 = 0

=> y ( y - 5 ) - 3 ( y - 5 ) = 0

=> ( y - 3 ) ( y - 5 ) = 0

=> y = 5, 3

=> If y = 5, then x = 15 / 5 = 3

=> If y = 3, then x = 15 / 3 = 5

=> x² + 5² = 3² + 5² = 9 + 25 = 31 or x² + 5² = 5² + 5² = 25 + 25 = 50.

Hope my answer helped !