A function is linear if it has a constant, additive rate of change for consecutive inputs. A function is exponential if it has a constant, multiplicative rate of change for consecutive inputs.
A function is linear if it has a constant, additive rate of change for consecutive inputs. A function is exponential if it has a constant, multiplicative rate of change for consecutive inputs. A quadratic function does not have a constant rate of change, but it is symmetric on each side of the vertex.