Answer:
The answer is A. [tex]\frac{3(x-21)}{(x+7)(x-7)}[/tex].
Step-by-step explanation:
To find the difference of this problem, start by simplifying the denominator, which will look like [tex]\frac{3}{x+7}-\frac{42}{(x+7)(x-7)}[/tex]. Next, multiply [tex]\frac{3}{x+7}[/tex] by [tex]\frac{x-7}{x-7}[/tex] to create a fraction with a common denominator in order to subtract from [tex]\frac{42}{(x+7)(x-7)}[/tex]. The problem will now look like [tex]\frac{3}{x+7}*\frac{x-7}{x-7}-\frac{42}{(x+7)(x-7)}[/tex].
Then, simplify the terms in the problem by first multiplying [tex]\frac{3}{x+7}[/tex] and [tex]\frac{x-7}{x-7}[/tex], which will look like [tex]\frac{3(x-7)}{(x+7)(x-7)}-\frac{42}{(x+7)(x-7)}[/tex]. The next step is to combine the numerators over the common denominator, which will look like [tex]\frac{3(x-7)-42}{(x+7)(x-7)}[/tex].
Next, simplify the numerator, and to simplify the numerator start by factoring 3 out of [tex]3(x-7)-42[/tex], which will look like [tex]\frac{3(x-7-14)}{(x+7)(x-7)}[/tex]. Then, subtract 14 from -7, which will look like [tex]\frac{3(x-21)}{(x+7)(x-7)}[/tex]. The final answer will be [tex]\frac{3(x-21)}{(x+7)(x-7)}[/tex].
