i know i will get two values of ex by factorization. but i am not being able to middle term factorize it.
It's not factorable. For it to be factorable over the integers the discriminant would need to be a perfect square.
$\displaystyle \begin{aligned}
b^2 - 4ac &= (-83)^2 - 4(21)34 \\
&= 6889 - 2856 \\
&= 4033
\end{aligned}$
... and 4033 is not a perfect square.