Firstly the general formula you can use on each of the x terms in the polynomial you are trying to differentiate is; f(x)=xn then f '(x)=nxn-1 where any constant, c, will differentiate to give 0. This formula basically states that you need to multiply x by it's power and then reduce that power by 1. If there is a coefficient then you still multiply x by it's power but you must remember to also take into account the coefficient e.g. if we have f(x)= 2x2 then we multiply 2x by 2 to get 4x and then reduce the power by one to get a final answer of f '(x)=4x1=4x. Therefore applying this to each of the terms in the given polynomial we get an answer of f '(x)= 9x2 - 6x-4 - (1/2)x-1/2