@C_R  but there are still no final expressions, maple hadn't calculated the roots and pi is still not subtituted. That is the problem which I am struggling to solve

@Thomas Richard 

Thank you!

Big thanks for all who answered, folks you'd made my day.

@C_R it worked for the small exponential expression, but for the large one still nothing.

You see,it worke for the little one but the big expression weren't calculated