Mister Exam

log2(2x-4)>3 inequation

A inequation with variable

The solution

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log(2*x - 4)    
------------ > 3
   log(2)       
$$\frac{\log{\left(2 x - 4 \right)}}{\log{\left(2 \right)}} > 3$$
log(2*x - 4)/log(2) > 3
Detail solution
Given the inequality:
$$\frac{\log{\left(2 x - 4 \right)}}{\log{\left(2 \right)}} > 3$$
To solve this inequality, we must first solve the corresponding equation:
$$\frac{\log{\left(2 x - 4 \right)}}{\log{\left(2 \right)}} = 3$$
Solve:
Given the equation
$$\frac{\log{\left(2 x - 4 \right)}}{\log{\left(2 \right)}} = 3$$
$$\frac{\log{\left(2 x - 4 \right)}}{\log{\left(2 \right)}} = 3$$
Let's divide both parts of the equation by the multiplier of log =1/log(2)
$$\log{\left(2 x - 4 \right)} = 3 \log{\left(2 \right)}$$
This equation is of the form:
log(v)=p

By definition log
v=e^p

then
$$2 x - 4 = e^{\frac{3}{\frac{1}{\log{\left(2 \right)}}}}$$
simplify
$$2 x - 4 = 8$$
$$2 x = 12$$
$$x = 6$$
$$x_{1} = 6$$
$$x_{1} = 6$$
This roots
$$x_{1} = 6$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} < x_{1}$$
For example, let's take the point
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$- \frac{1}{10} + 6$$
=
$$\frac{59}{10}$$
substitute to the expression
$$\frac{\log{\left(2 x - 4 \right)}}{\log{\left(2 \right)}} > 3$$
$$\frac{\log{\left(-4 + \frac{2 \cdot 59}{10} \right)}}{\log{\left(2 \right)}} > 3$$
log(39/5)    
--------- > 3
  log(2)     

Then
$$x < 6$$
no execute
the solution of our inequality is:
$$x > 6$$
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Solving inequality on a graph