(1)5^(n+1)÷5^(3n+1)
=5^(n+1-3n-1)
=5^(-2n)
=(1/25)^n
(2)10^5÷10^(-1)×10^0
=10^(5+1+0)=10^6=1000000
(3)(1/3)^0÷(-1/3)^-2
=(1/3)^0÷(1/3)^-2
=(1/3)^(0+2)
=(1/3)^2
=1/9