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log2*(x^2-5)*log3^2*(7-x)+3log2*(x^2-5)-2log3^2*(7-x)-6=0 equation

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Numerical solution:

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The solution

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       / 2    \    2                       / 2    \        2                   
log(2)*\x  - 5/*log (3)*(7 - x) + 3*log(2)*\x  - 5/ - 2*log (3)*(7 - x) - 6 = 0
$$\left(- \left(7 - x\right) 2 \log{\left(3 \right)}^{2} + \left(\left(x^{2} - 5\right) \log{\left(2 \right)} \log{\left(3 \right)}^{2} \left(7 - x\right) + \left(x^{2} - 5\right) 3 \log{\left(2 \right)}\right)\right) - 6 = 0$$
Detail solution
Given the equation:
$$\left(- \left(7 - x\right) 2 \log{\left(3 \right)}^{2} + \left(\left(x^{2} - 5\right) \log{\left(2 \right)} \log{\left(3 \right)}^{2} \left(7 - x\right) + \left(x^{2} - 5\right) 3 \log{\left(2 \right)}\right)\right) - 6 = 0$$
transform:
Take common factor from the equation
$$- \left(x \log{\left(3 \right)}^{2} - 7 \log{\left(3 \right)}^{2} - 3\right) \left(x^{2} \log{\left(2 \right)} - 5 \log{\left(2 \right)} - 2\right) = 0$$
Because the right side of the equation is zero, then the solution of the equation is exists if at least one of the multipliers in the left side of the equation equal to zero.
We get the equations
$$- x^{2} \log{\left(2 \right)} + 2 + 5 \log{\left(2 \right)} = 0$$
$$x \log{\left(3 \right)}^{2} - 7 \log{\left(3 \right)}^{2} - 3 = 0$$
solve the resulting equation:
1.
$$- x^{2} \log{\left(2 \right)} + 2 + 5 \log{\left(2 \right)} = 0$$
This equation is of the form
a*x^2 + b*x + c = 0

A quadratic equation can be solved
using the discriminant.
The roots of the quadratic equation:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where D = b^2 - 4*a*c - it is the discriminant.
Because
$$a = - \log{\left(2 \right)}$$
$$b = 0$$
$$c = 2 + 5 \log{\left(2 \right)}$$
, then
D = b^2 - 4 * a * c = 

(0)^2 - 4 * (-log(2)) * (2 + 5*log(2)) = 4*(2 + 5*log(2))*log(2)

Because D > 0, then the equation has two roots.
x1 = (-b + sqrt(D)) / (2*a)

x2 = (-b - sqrt(D)) / (2*a)

or
$$x_{1} = - \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}}$$
$$x_{2} = \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}}$$
2.
$$x \log{\left(3 \right)}^{2} - 7 \log{\left(3 \right)}^{2} - 3 = 0$$
Expand brackets in the left part
-3 - 7*log3^2 + x*log3^2 = 0

Move free summands (without x)
from left part to right part, we given:
$$x \log{\left(3 \right)}^{2} - 7 \log{\left(3 \right)}^{2} = 3$$
Divide both parts of the equation by (-7*log(3)^2 + x*log(3)^2)/x
x = 3 / ((-7*log(3)^2 + x*log(3)^2)/x)

We get the answer: x3 = 7 + 3/log(3)^2
The final answer:
$$x_{1} = - \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}}$$
$$x_{2} = \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}}$$
$$x_{3} = \frac{3}{\log{\left(3 \right)}^{2}} + 7$$
Rapid solution [src]
        ______________ 
     -\/ 2 + 5*log(2)  
x1 = ------------------
           ________    
         \/ log(2)     
$$x_{1} = - \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}}$$
       ______________
     \/ 2 + 5*log(2) 
x2 = ----------------
          ________   
        \/ log(2)    
$$x_{2} = \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}}$$
              2   
     3 + 7*log (3)
x3 = -------------
           2      
        log (3)   
$$x_{3} = \frac{3 + 7 \log{\left(3 \right)}^{2}}{\log{\left(3 \right)}^{2}}$$
x3 = (3 + 7*log(3)^2)/log(3)^2
Sum and product of roots [src]
sum
    ______________     ______________            2   
  \/ 2 + 5*log(2)    \/ 2 + 5*log(2)    3 + 7*log (3)
- ---------------- + ---------------- + -------------
       ________           ________            2      
     \/ log(2)          \/ log(2)          log (3)   
$$\left(- \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}} + \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}}\right) + \frac{3 + 7 \log{\left(3 \right)}^{2}}{\log{\left(3 \right)}^{2}}$$
=
         2   
3 + 7*log (3)
-------------
      2      
   log (3)   
$$\frac{3 + 7 \log{\left(3 \right)}^{2}}{\log{\left(3 \right)}^{2}}$$
product
   ______________    ______________          2   
-\/ 2 + 5*log(2)   \/ 2 + 5*log(2)  3 + 7*log (3)
------------------*----------------*-------------
      ________          ________          2      
    \/ log(2)         \/ log(2)        log (3)   
$$- \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}} \frac{\sqrt{2 + 5 \log{\left(2 \right)}}}{\sqrt{\log{\left(2 \right)}}} \frac{3 + 7 \log{\left(3 \right)}^{2}}{\log{\left(3 \right)}^{2}}$$
=
               /         2   \ 
-(2 + log(32))*\3 + 7*log (3)/ 
-------------------------------
                   2           
         log(2)*log (3)        
$$- \frac{\left(2 + \log{\left(32 \right)}\right) \left(3 + 7 \log{\left(3 \right)}^{2}\right)}{\log{\left(2 \right)} \log{\left(3 \right)}^{2}}$$
-(2 + log(32))*(3 + 7*log(3)^2)/(log(2)*log(3)^2)
Numerical answer [src]
x1 = 9.48560634907067
x2 = -2.80809367396779
x3 = 2.80809367396779
x3 = 2.80809367396779