$\displaystyle y = \frac{3x+4}{x-1}$

a. Determine all values for $\displaystyle x$ for which $\displaystyle \frac{dy}{dx}$ exists.

b. Find an expression for $\displaystyle \frac{dy}{dx}$.

Here are my answers..are they correct?

a. All real numbers not equal to 1

b. $\displaystyle \frac{-5}{(x-1)^2}$