if you mean 5^2 and not 5^2i then
5^2 just means 5 times itself,twice or 5 times 5 or 25
if you meant 5^2i
i=√-1
so law of exponents says a^(xz)=(a^x)^z so
5^2i=(5^2)^i or (25)^i
the answer (if you wanted 5^2i) is 25^i
IF YOU MEANT 5^2 then the answer is 25