$\left(-\infty,3\right]$\left(-\infty,3\right]

$\left(-\infty,5\right]$\left(-\infty,5\right]

$\left(-\infty,11\right]$\left(-\infty,11\right]

$\left[6,+\infty\right)$\left[6,+\infty\right)