I have the following quadratic equation:

$\displaystyle \frac{1}{2}kd^2-\mu_kmgl-\frac{1}{2}mv_B^2=0$

I would like to solve for d.

So I wanna use this formula:

$\displaystyle x=\frac{-b\pm\sqrt{b^2-4ac\ }}{2a}$

Now I know that here I have:

$\displaystyle a=\frac{1}{2}k$

However is it true to say that:

$\displaystyle b=0$

$\displaystyle c=-\mu_kmgl-\frac{1}{2}mv_B^2$

???? I'm wondering if c can include operators like plus and minus?