Solving a simple equation, is it normal?

[stardrive]

I was trying to solve the first equation from the pic with HP Prime (latest firmware).

But solution never came out.

However, the second one (simply changed variable's location) works.

Unless the numbers on an equation are small, it works fine.
(eg. solve(10=5/pi*x^2))

If anyone could tell me why this happened, it would be very helpful for me.

Thanks.

*same equation: http://www.wolframalpha.com/input/?i=sol...-12*x%5E2)