A linear function is a polynomial function of degree 1 (1,2,3,4,5,6,....) A quadratic function is a polynomial function of degree 2 (1,4,9,16,25,49,64,81,...) A exponential function is not a polynomial function (we may imagine a infinity degree) (1,2,4,8,16,32,64,128,256,512,1024,...)