Question

se x² + y² = 34 e ( x + y)² = 64 qual sera o resultado de 5xy?

Answer 1

(x + y)² = 64
(x + y)(x + y) = 64
x² + 2xy + y² = 64
(x² + y²) + 2xy = 64
34 + 2xy = 64
2xy = 30
xy = 25
5 . xy = 25 . 5
5xy = 125