Question

Знайдіть х+у, якщо x3+y3=9, а x2y+xy2 = 6,​

Answer 1

(x+y)³=x³+3x²y+3xy²+y³⇒(x+y)³=x³+y³+3(x²y+xy²)=9+3·6=27

(x+y)³=27

x+y=3