0 ≤ sin^2x ≤ 1 0 ≤ sin^4x ≤ 1 ... 0 ≤ sin^(28)x ≤ 1 [b]0≤ 7*sin^(28)x ≤ 7[/b] Аналогично 0 ≤ cos^2x ≤ 1 0 ≤ cos^4x ≤ 1 ... [b]0 ≤ cos^(14)x ≤ 1[/b] Складываем 0 ≤ 7*sin^(28)x+cos^(14)x ≤ 7+1=8 8 < 9 [b]Уравнение не имеет корней.[/b]