find the equation of the tangent line to $\displaystyle f(x) = x+\sqrt{x}$ at (4,6)

$\displaystyle \frac{(x+\sqrt{x})-(4+\sqrt{4})}{x-4}$

= $\displaystyle \frac{x-4+\sqrt{x}-\sqrt{4}}{x-4}$

why am I havin so much trouble getting that denominator out of there