OSX Preview: is able to display DRM protected PDF files? (mainly concerned about Adobe DRM)
HINT $\ $ For $\rm\ z = \sqrt{x}\ $ the fraction is $\rm\displaystyle\ \frac{z^2-9}{z-3}\ = \ \cdots$
HINT $\ $ For $\rm\ z = \sqrt{x}\ $ the fraction is $\rm\displaystyle\ \frac{z^2-9}{z-3}\ = \ \cdots$