Respuesta :

DeanR

Answer:

Step-by-step explanation:

I'll just write log for log base 10.  The important rules about logarithms we need to know are:

[tex] a \log b = \log( b^a) [/tex]

[tex] \log a + \log b = \log( ab) [/tex]

and at the end we'll need something like

[tex]\log a = \log b \implies a=b[/tex]

Suitably armed we can begin,

[tex] \left( 1 + \dfrac{1}{2x} \right) \log 3 + \log 2 = \log (27 - 3^{1/x}) [/tex]

First rule,

[tex] \log 3^{ 1 + 1/2x}  + \log 2 = \log (27 - 3^{1/x}) [/tex]

Second rule,

[tex] \log 2(3^{ 1 + 1/2x})  = \log (27 - 3^{1/x}) [/tex]

Third rule,

[tex] 2(3^{ 1 + 1/2x})  = 27 - 3^{1/x} [/tex]

We can rewrite this to be a quadratic equation in [tex]y=3^{1/2x}[/tex].

[tex]  6 (3^{1/2x})  = 27 -  (3^{1/2x})^2 [/tex]

[tex]y^2 +6y - 27 =0[/tex]

[tex](y - 3)(y+9)=0[/tex]

[tex]y=3 \textrm{ or } y=-9[/tex]

First solution:

[tex]3^{1/2x} = 3 = 3^{1}[/tex]

[tex]1/2x = 1[/tex]

[tex]1=2x[/tex]

[tex]x = 1/2[/tex]

Second solution,

[tex]3^{1/2x} = -9[/tex]

No real powers of 3 will be negative, no solution here.

Answer: x=1/2

Check:  

1 + 1/2x = 2 so the left side is log 2(3²) = log 18

Right side, log(27-3^2) = log 18  √