[tex]\bf \textit{difference of squares}
\\ \quad \\
(a-b)(a+b) = a^2-b^2\qquad \qquad
a^2-b^2 = (a-b)(a+b)\\\\
-------------------------------\\\\
\cfrac{11}{x^2-25}+\cfrac{4}{x+5}=\cfrac{3}{x-5}\implies \cfrac{11}{x^2-5^2}+\cfrac{4}{x+5}=\cfrac{3}{x-5}[/tex]
[tex]\bf \cfrac{11}{(x-5)(x+5)}+\cfrac{4}{x+5}=\cfrac{3}{x-5}\impliedby
\begin{array}{llll}
\textit{notice, LCD is }(x-5)(x+5)\\
\textit{so let's multiply all by it}\\
\textit{to toss the denominators}
\end{array}[/tex]
[tex]\bf (x-5)(x+5)\left( \cfrac{11}{(x-5)(x+5)}+\cfrac{4}{x+5} \right)=(x-5)(x+5)\left( \cfrac{3}{x-5} \right)
\\\\\\
11+4(x-5)=3(x+5)\implies 11+4x-20=3x+15
\\\\\\
4x-9=3x+15\implies x=24[/tex]
