What is the difference?

[tex]\[
\frac{x}{x^2-16} - \frac{3}{x-4}
\][/tex]

A. [tex]\(\frac{2(x+6)}{(x+4)(x-4)}\)[/tex]

B. [tex]\(\frac{-2(x+6)}{(x+4)(x-4)}\)[/tex]

C. [tex]\(\frac{x-3}{(x+5)(x-4)}\)[/tex]

D. [tex]\(\frac{-2(x-6)}{(x+4)(x-4)}\)[/tex]



Answer :

To find the difference between the first two terms:
[tex]\[ \frac{x}{x^2 - 16} - \frac{3}{x - 4}, \][/tex]
we'll proceed step-by-step.

### Step 1: Factorize the denominator
Firstly, notice that [tex]\(x^2 - 16\)[/tex] can be factored as:
[tex]\[ x^2 - 16 = (x + 4)(x - 4). \][/tex]
Thus the first term becomes:
[tex]\[ \frac{x}{x^2 - 16} = \frac{x}{(x + 4)(x - 4)}. \][/tex]

### Step 2: Rewrite the second fraction
The second term is:
[tex]\[ \frac{3}{x - 4}. \][/tex]
To combine this with the first term, we'll write it with a common denominator. Since the common denominator is [tex]\( (x + 4)(x - 4) \)[/tex], we rewrite the second term as:
[tex]\[ \frac{3}{x - 4} = \frac{3(x + 4)}{(x + 4)(x - 4)}. \][/tex]

### Step 3: Subtract the fractions
Now we have the two fractions with a common denominator:
[tex]\[ \frac{x}{(x + 4)(x - 4)} - \frac{3(x + 4)}{(x + 4)(x - 4)}. \][/tex]
Combine them into a single fraction:
[tex]\[ \frac{x - 3(x + 4)}{(x + 4)(x - 4)}. \][/tex]

### Step 4: Simplify the numerator
Simplify the numerator by distributing and combining like terms:
[tex]\[ x - 3(x + 4) = x - 3x - 12 = -2x - 12. \][/tex]

### Step 5: Write final expression
The simplified form of the difference is:
[tex]\[ \frac{-2x - 12}{(x + 4)(x - 4)}. \][/tex]

We can also factor out a common factor of [tex]\( -2 \)[/tex] from the numerator:
[tex]\[ \frac{-2(x + 6)}{(x + 4)(x - 4)}. \][/tex]

Thus, the difference,
[tex]\[ \frac{x}{x^2-16} - \frac{3}{x-4} \][/tex]
is:
[tex]\[ \frac{2(-x-6)}{x^2 - 16}. \][/tex]

Hence, the result is:
[tex]\[ \boxed{\frac{2(-x - 6)}{x^2-16}}. \][/tex]