It is 52 because when roundest to the whole number 52 is closest 
 
        
             
        
        
        
It would equal 0.75 and as a fraction it is 3/4
 
        
                    
             
        
        
        
Step-by-step explanation:

 
        
             
        
        
        
I don't know what method is referred to in "section 4.3", but I'll suppose it's reduction of order and use that to find the exact solution. Take 

, so that 

 and we're left with the ODE linear in 

:

Now suppose 

 has a power series expansion



Then the ODE can be written as


![\displaystyle\sum_{n\ge2}\bigg[n(n-1)a_n-(n-1)a_{n-1}\bigg]x^{n-2}=0](https://tex.z-dn.net/?f=%5Cdisplaystyle%5Csum_%7Bn%5Cge2%7D%5Cbigg%5Bn%28n-1%29a_n-%28n-1%29a_%7Bn-1%7D%5Cbigg%5Dx%5E%7Bn-2%7D%3D0)
All the coefficients of the series vanish, and setting 

 in the power series forms for 

 and 

 tell us that 

 and 

, so we get the recurrence

We can solve explicitly for 

 quite easily:

and so on. Continuing in this way we end up with

so that the solution to the ODE is

We also require the solution to satisfy 

, which we can do easily by adding and subtracting a constant as needed:
 
 
        
        
        
1: Identify the angle. 
<em>The following angle is a 90.</em>
2: Set up the equation.
<em>x + (3x + 10) = 90</em>
3: Combine like terms.
<em>4x + 10 = 90</em>
4: Solve for x.
<em>4x + 10 = 90</em>
<em>      -10 =   - 10</em>
<em>--------------------------</em>
<em>4x = 80</em>
<em>------------------</em>
<em>4          4</em>
<em>x = 20</em>
Your answer is x = 20. 
Hope this helps! Have a good day/night! c: