Ta có bảng sau:
a | \(\frac{1}{7}\) | \(\frac{1}{7}\) | \(\frac{1}{7}\) | \(\frac{2}{7}\) | \(\frac{2}{7}\) | \(\frac{2}{7}\) | \(\frac{3}{7}\) | \(\frac{3}{7}\) | \(\frac{3}{7}\) |
b | \(\frac{6}{7}\) | \(\frac{5}{7}\) | \(\frac{4}{7}\) | \(\frac{6}{7}\) | \(\frac{5}{7}\) | \(\frac{4}{7}\) | \(\frac{6}{7}\) | \(\frac{5}{7}\) | \(\frac{4}{7}\) |
x | \(1\) | \(\frac{6}{7}\) | \(\frac{5}{7}\) | \(\frac{8}{7}\) | \(1\) | \(\frac{6}{7}\) | \(\frac{9}{7}\) | \(\frac{8}{7}\) | \(1\) |
Từ bảng trên ta thấy: \(M=\left\{1;\frac{6}{7};\frac{5}{7};\frac{8}{7};\frac{9}{7}\right\}\)
Mà M nhận giá trị STN => M=1
Ta có bảng sau:
a | \(\frac{1}{7}\) | \(\frac{1}{7}\) | \(\frac{1}{7}\) | \(\frac{2}{7}\) | \(\frac{2}{7}\) | \(\frac{2}{7}\) | \(\frac{3}{7}\) | \(\frac{3}{7}\) | \(\frac{3}{7}\) |
b | \(\frac{6}{7}\) | \(\frac{5}{7}\) | \(\frac{4}{7}\) | \(\frac{6}{7}\) | \(\frac{5}{7}\) | \(\frac{4}{7}\) | \(\frac{6}{7}\) | \(\frac{5}{7}\) | \(\frac{4}{7}\) |
x | \(1\) | \(\frac{6}{7}\) | \(\frac{5}{7}\) | \(\frac{8}{7}\) | \(1\) | \(\frac{6}{7}\) | \(\frac{9}{7}\) | \(\frac{8}{7}\) | \(1\) |
Từ bảng trên ta có: \(M=\left\{1;\frac{6}{7};\frac{5}{7};\frac{8}{7};\frac{9}{7}\right\}\)