$\displaystyle \left(-\infty, \frac{2}{7} \right)$\displaystyle \left(-\infty, \frac{2}{7} \right)

$\displaystyle \left( \frac{2}{7},+\infty \right)$\displaystyle \left( \frac{2}{7},+\infty \right)

$\displaystyle \left(-\infty, \frac{3}{8} \right)$\displaystyle \left(-\infty, \frac{3}{8} \right)

$\displaystyle \left( \frac{3}{8},+\infty \right)$\displaystyle \left( \frac{3}{8},+\infty \right)