Help needed please! Is this correct? Solve the quadratic equation

this is not a quadratic equation.

Perhaps you want to rationalize the denominator?

 

$$\\\frac{4}{\sqrt3-5}\\\\
=\frac{4}{\sqrt3-5}\times \frac{\sqrt3+5}{\sqrt3+5}\\\\
=\frac{4(\sqrt3+5)}{3-25}\\\\
=\frac{4(\sqrt3+5)}{-22}\\\\
=\frac{-2(\sqrt3+5)}{11}\\\\
=\frac{-2\sqrt3-10}{11}\\\\$$

 

So it seems you have rationalized the denominator correctly :)