Derive an expression for the unit step response of the system;

g(s)=1/(s^2 +2s +17)

Then sketch this response and compare it to the response predicted using MATLAB.

I have found many examples on this type of question however all of them seem to have the numerator and the last number in the denominator to be the same. So the natural freqency(omega) being the square root of the numerator....? from my understanding without the natural frequency i cannot find the damping factor and therefore cannot fill the blanks in the response for the unit step...?

Any help will be great, thanks