Question

sabendo que a² + b² = 13 e que ⅔ ab = - 4,

determine o valor de (a +b)²

Answer 1

⅔ ab = - 4. ==> ×(3)

2ab = -12

(a+b)² =a²+b² +2ab

(a+b)² = 13 - 12

(a+b)² = 1