Question

determinati x si y care au suma egala cu 2 si produsul cu -15

Answer 1

x+y = 2<br />x*y = -15<br />x = 2-y<br />(2-y)*y = -15 => 2y - y² + 15 = 0<br />-y² + 2y + 15 = 0<br />delta = b²-4ac<br />delta = 2² -4*(-1)*15 = 4+60 = 64<br />x1,x2 = (-b±√delta)/2a = (-2±√64)/(-2) => x1 = (-2-8)/(-2) = 5, x2 = (-2+8)/(-2) = -3<br />S = {5;-3}