How would I solve the equation 25^x = 5^(4x+1)?

You would have to rewrite 25 as 5^2 hence 25^x = (5^2)^x = 5^(2*x).

Then 5^(2x) = 5^(4x+1) and therefore 2x = 4x + 1 hence 2x = -1 hence x = -1 / 2.