Originally Posted by

**ThePerfectHacker** Let this be your first and last time you make this mistake. It leads to mathematical death! I used division by zero. How? Look at what I did. I brought $\displaystyle c$ other to the other side $\displaystyle c^{-1}$. Now $\displaystyle c^{-1}$ does not exist when $\displaystyle c=0$. So I really should have considered two cases. Case 1, is $\displaystyle c>0$ and you can apply my argument. Case 2, is $\displaystyle c=0$ and you need to apply a different argument. How will it go when $\displaystyle c=0$?