\( \frac{2 X^{5}}{(X-Y)^{5}}+\frac{X^{4}}{(X-Y)^{4}}+\frac{4 X^{5} Y}{(X-Y)^{6}} \)
\( = \frac{2 X^{5}(X-Y)}{(X-Y)^{6}}+\frac{X^{4}(X-Y)^2}{(X-Y)^{6}}+\frac{4 X^{5} Y}{(X-Y)^{6}} \)
\(= \frac{2 X^{6}-2 X^{5}Y+X^{4}(X^2-2XY+Y^2)+4X^5Y}{(X-Y)^{6}}\)
\( = \frac{2 X^{6}-2 X^{5}Y+X^{6}-2X^5Y+X^4Y^2+4X^5Y}{(X-Y)^{6}}\)
\( = \frac{3 X^{6}+X^4Y^2}{(X-Y)^{6}}\)