b$.$ Mom & Pop has one bond outstanding, which matures in $2$ years. It has a $5\%$ annual coupon and is currently

trading at par. The cumulative default probability for this bond is $1\%$ in one year, and $1\mathrm{.}2\%$ in two years, and

the expected recovery rate is a constant $40\%.$ Determine Mom & Pop's cost of debt capital. $(6$ points$)$

For a face value of $100,$ a $5\%$ coupon implies a $$5$ promised payment over two years, plus a principal

payment of $100$ in two years. A cumulative probability of default in two years of $1\mathrm{.}2\%$ and a $1\%$ in one year

implies an unconditional probability of default of $0\mathrm{.}2\%$ in two years. So the get the cost of debt, we solve the

following equation:

$100=\frac{5**0\mathrm{.}99+105**0\mathrm{.}4**0\mathrm{.}01}{1+r_d}+\frac{105**0\mathrm{.}988+105**0\mathrm{.}4**0\mathrm{.}002}{(1+r_d{)}^2}$

And we get $r_d=4\mathrm{.}6144\%$

How do I solve for rd using quadratic formula?