The least common denominator of two given rational expression are 4x, (x-3) and (x+3).
What is the least common denominator of two rational terms?
The factored denominator of two rational terms are called least common denominator of two rational numbers.
How to find the least common denominator of two rational terms?
To find the least common denominator of two rational terms, we factor the expression and multiply all the distinct factors.
According to the given question
We have two rational expressions
[tex]\frac{9}{4x^{2} -12x}[/tex] and [tex]\frac{7x}{x^{2} -9}[/tex]
Now let's factorize the denominators
[tex]4x^{2} -12x =4x(x-3)[/tex]
and, [tex]x^{2} -9=(x+3)(x-3)[/tex]
Therefore,
[tex]\frac{9}{4x^{2} -12x}+\frac{7x}{x^{2} -9}[/tex]
⇒[tex]\frac{9}{4x(x-3)} +\frac{7x}{(x-3)(x+3)}[/tex]
⇒[tex]\frac{9(x+3)+7x(4x)}{4x(x-3)(x+3)}[/tex]
Therefore, the least common denominator of two given rational expression are 4x, (x-3) and (x+3).
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