Show that

8^x =square root 2

5^x=1/square root 25 (3)

If you mean solve for x, then

8^x = √2
(2^3)^x = 2^(1/2)
2^(3x) = 2^(1/2)
3x = 1/2
x = 1/6

5^x = 1/√25
5^x = 1/5
5^x = 5^(-1)
x = -1

don't know what the (3) means