Solve the following quadratic: `21 x^2+9x+1=0`

Explanation

Recall that the roots of quadratic equation `a x^{2}+b x+c=0`, where `a \ne 0`, are given by
$$ x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a} $$
Here, `a=21, b=9` and `c=1`
$$
\begin{aligned}
&\rightarrow x-\frac{-9 \pm \sqrt{9^{2}-4(21)}}{2(21)} \\
...