$$\frac{ -6 \pm \sqrt{ 6 { x }^{ 2 } +4 \times 6 \times 36 } }{ 2 \times 6 }$$
$\frac{-6±\sqrt{6\left(x^{2}+144\right)}}{12}$
$\frac{\frac{\mathrm{d}}{\mathrm{d}x}(-6±\sqrt{6\left(x^{2}+144\right)})}{12}$
