Question 488974
You made only one mistake, but of course that is one too many.

5*(sqrt of 5)= 25^4x-1 
now you divide both sides by 5 and get (sq rt of 5)=5^4x-1 

When you divide 25^y by 5 you do not get 5^y, you get 5^(2y-1) due to 2 rules for computing these exponent operations..
1. 25^y = (5^2)^y = 5^(2y)
2. (5^z)/5 = 5^(z-1).

Now apply this to your given problem and solve for x similar to how you did before.  Hint: it's still a fraction, slighly larger.