Part A)
x = 0 because (2^6)^0 = 2^0 = 1
Any number to the 0 exponent is equal 1, except 0
Part B)
x is all real number (5^0)^x will be always equal 1 doesn't matter x is what numbers.
For example:
If x = 1 then (5^0)^1 = 5^0 = 1
If x = -1 then (5^0)^-1 = 5^0 = 1
If If x = 0 then (5^0)^0 = 5^0 = 1 and so on....