Given
[tex]\frac{3x}{x+9}+\frac{x}{x-4}[/tex]To find the sum of the rational expressions.
Explanation:
It is given that,
[tex]\frac{3x}{x+9}+\frac{x}{x-4}[/tex]Then,
[tex]\begin{gathered} \frac{3x}{x+9}+\frac{x}{x-4}=\frac{3x(x-4)+x(x+9)}{(x+9)(x-4)} \\ =\frac{3x^2-12x+x^2+9x}{x^2+9x-4x-36} \\ =\frac{4x^2-3x}{x^2+5x-36} \end{gathered}[/tex]Hence, the answer is option A).