Given the function f(x)=x-21, x20, complete parts a through c.(a) Find an equation for f(x).(b) Graph f and f in the same rectangular coordinate system.(c)

Given the function f(x)=x²-21, x20, complete parts a through c.(a) Find an equation for f¹(x).(b) Graph f and f¹ in the same rectangular coordinate system.(c) Use interval notation to give the domain and the range of f and f¹.(a) Find f¹(x).(Type an exact answer, using radicals as needed.)