Graph of a constant function, f( x) = k, where k is constant, is a line parallel to x-axis. Domain = R & Range = { k }.
Graph of polynomial f( x) = a0 + a1x + a2x 2 +...+ an x n where n is a nonnegative integer & a0, a1, a2,..., an∈ R., depends on f( x). Domain = R & Range = depends on f( x).