Question

Calcule o valor de x²+y², sabendo que (x-y)² =30 e xy=18

Answer 1

(x-y)² = 30
x² - 2xy + y² = 30
x² + y² - 2.18 = 30
x² + y² - 36 = 30
x² + y² = 30 + 36
x² + y² = 66

Answer 2

( x - y)²  = x² - xy + y² ou ( x² + y² )- xy = 30
( x² + y² ) - ( 18) = 30
x² + y² = 30 + 18
x² + y²  = 48 ******