Question

Se a² + b² = 34 e (a + b)² = 64, entao o valor de 6ab vale ?

Answer 1

A² + 2ab +b² = 64
A² + b² = 64 -2ab
34 = 64 - 2ab
-30= -2ab .(-1)
2ab=30 multiplicando ambos os lados por 3
6ab = 90

Answer 2

a²+b²=34 e (a+b)²=64 

(a+b)²=(a+b)×(a+b)=a²+2ab+b²

a²+b²=34 e a²+b²=64-2ab
entao,
34=64-2ab
-30=-2ab(×-1)
30=2ab
ab=15
6ab=6×15
6ab=90