Question 67161
<pre><font size = 5><b>log<sub>4</sub>(4x) + 2·log<sub>4</sub>(x + 3) = 2

Get the left side to a single logarithm.

Use the rule

 n·log<sub>B</sub>A = log<sub>B</sub>A<sup>n</sup>  

to rewrite the second term:

log<sub>4</sub>(4x) + log<sub>4</sub>(x + 3)<sup>2</sup> = 2

Use the rule:

 log<sub>B</sub>A + log<sub>B</sub>C = log<sub>B</sub>(AC) to rewrite the
whole left side:

        log<sub>4</sub>[4x(x + 3)<sup>2</sup>] = 2

Use the rule:

log<sub>B</sub>A = C can be rewritten as A = B<sup>C</sup> 

to rewrite the equation:

          4x(x + 3)<sup>2</sup> = 4<sup>2</sup>

    4x(x + 3)(x + 3) = 16

4x(x<sup>2</sup> + 3x + 3x + 9) = 16

     4x(x<sup>2</sup> + 6x + 9) = 16

To make things easier, divide both sides by 4

      x(x<sup>2</sup> + 6x + 9) = 4     

       x<sup>3</sup> + 6x<sup>2</sup> + 9x = 4

   x<sup>3</sup> + 4x<sup>2</sup> + 9x - 4 = 0 

There is no easy way to solve that by hand, so we
use a TI-82 or higher calculator and get

            x = 0.3553013976 
Edwin</pre>