The least common denominator (LCD) is defined as the least common multiple of the denominators of a set of fractions. In this case, we have the fractions:
[tex]\frac{3}{x}, \frac{2}{x-11}[/tex]
So the LCD here is the product of [tex]x \ and \ x-11[/tex]. Therefore:
[tex]LCD=x(x-11)[/tex]
So we can write equivalent expressions as:
[tex]\frac{3(x-11)}{x(x-11)}, \frac{2x}{x(x-11)}[/tex]
As you can see, both expression has the same denominator which is the LCD.