To subtract these fractions, we need to find a common denominator. First, factor the denominators if possible. Then, rewrite each fraction with the common denominator and perform the subtraction. Finally, simplify the resulting fraction if possible.
Step 1: Factor the Denominators
First, we factor the denominators of the given fractions:
\[
\frac{4x}{16x^2 - 9} - \frac{4}{3 - 4x}
\]
The denominator \(16x^2 - 9\) can be factored as a difference of squares:
\[
16x^2 - 9 = (4x + 3)(4x - 3)
\]
Step 2: Rewrite the Fractions with a Common Denominator
Next, we rewrite each fraction with the common denominator \((4x + 3)(4x - 3)\):
\[
\frac{4x}{(4x + 3)(4x - 3)} - \frac{4}{3 - 4x}
\]
Notice that \(3 - 4x\) can be rewritten as \(-(4x - 3)\). Thus, the second fraction becomes:
\[
\frac{4}{-(4x - 3)} = -\frac{4}{4x - 3}
\]
Rewriting the second fraction with the common denominator:
\[
-\frac{4(4x + 3)}{(4x + 3)(4x - 3)}
\]