x_(1)+x_(2)...+x_(239)=S
Заменяем
x_(1) на S - x_(1)
x_(2) на S - x_(2)
…
x_(239) на S - x_(239)
Получаем
(S - x_(1))+( S - x_(2))+...+( S - x_(239))=S
239S-S=S
237S=0
S=0
Находим произведение
x_(1)*x_(2)*...*x_(239)=(S-x_(1))(S-x_(2))…(S-x_(239)) x_(1)*x_(2)*...*x_(239)=(0-x1)(0-x2)*…(0-x2009)
x_(1)*x_(2)*...*x_(239)=- x_(1)*x_(2)*...*x_(239)
2*x_(1)*x_(2)*...*x_(239)=0
x_(1)*x_(2)*...*x_(239)=0
О т в е т.x_(1)*x_(2)*...*x_(239)=0