What is [tex]$3 \log _2 x-\left(\log _2 3-\log _2(x+4)\right)$[/tex] written as a single logarithm?

A. [tex]\log _2\left[\frac{x^3(x+4)}{3}\right][/tex]

B. [tex]\log _2\left(\frac{3 x^3}{x+4}\right)[/tex]

C. [tex]\log _2\left[\frac{x^3}{3(x+4)}\right][/tex]

D. [tex]\log _2\left(\frac{x^3}{3+(x+4)}\right)[/tex]



Answer :

Let's convert the given expression [tex]\(3 \log_2(x) - \left(\log_2(3) - \log_2(x + 4)\right)\)[/tex] into a single logarithm step by step.

1. Rewrite [tex]\(3 \log_2(x)\)[/tex]:
[tex]\[ 3 \log_2(x) = \log_2(x^3) \][/tex]
Using the power rule of logarithms, [tex]\(a \log_b(x) = \log_b(x^a)\)[/tex].

2. Simplify [tex]\(\log_2(3) - \log_2(x + 4)\)[/tex]:
[tex]\[ \log_2(3) - \log_2(x + 4) = \log_2\left(\frac{3}{x + 4}\right) \][/tex]
Using the quotient rule of logarithms, [tex]\(\log_b(a) - \log_b(b) = \log_b\left(\frac{a}{b}\right)\)[/tex].

3. Combine the results from steps 1 and 2:
[tex]\[ 3 \log_2(x) - \left(\log_2(3) - \log_2(x + 4)\right) = \log_2(x^3) - \log_2\left(\frac{3}{x + 4}\right) \][/tex]

4. Combine the logarithms using the quotient rule again:
[tex]\[ \log_2(x^3) - \log_2\left(\frac{3}{x + 4}\right) = \log_2\left(\frac{x^3}{\frac{3}{x + 4}}\right) \][/tex]

5. Simplify inside the logarithm:
[tex]\[ \frac{x^3}{\frac{3}{x + 4}} = x^3 \cdot \frac{x + 4}{3} = \frac{x^3 (x + 4)}{3} \][/tex]

6. Write the final combined logarithm:
[tex]\[ \log_2\left( \frac{x^3 (x + 4)}{3} \right) \][/tex]

Thus, the expression [tex]\(3 \log_2(x) - \left(\log_2(3) - \log_2(x + 4)\right)\)[/tex] written as a single logarithm is:
[tex]\[ \boxed{\log_2\left( \frac{x^3 (x + 4)}{3} \right)} \][/tex]

So, the correct option from the given multiple choices is:
[tex]\[ \log_2\left[\frac{x^3 (x + 4)}{3}\right] \][/tex]
Thus, the correct answer is option 1.