Question

Sabendo que (x+y)² = 144 e que x² + y² = 110, determine o valor de x.y

Answer 1

x² + y² = 110

(x+y)² = 144 ==> x²+2x.y+y²=144

x²+y²+ 2 * x.y =144

110 + 2 * x.y =144

2 * x.y = 34

x.y= 17