I am confused

Find the indicated ouputs: f(n)=2^n a. f(5)= b. f(0)= f(n)=5^n a. f(4)= b. f(1)= f(n)=(-2)^n a. f(3)= b. f(0)= f(n)= -2^n a. f(3)= b. f(0)= I am so confused because my teacher didn't explain what these are please help :(