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Hi there,

 

I'm having trouble solve for x in this equation.

I've checked the equation a few times, it's correct!

 

I appreciate your help!

Guest Oct 25, 2018
 #1
avatar+90995 
+1

Here's my  best attempt :

 

0   =    w         ( L^2x^2     -   x^4      -  7L^4  )

         ____        ______        ___         _____

         EI6L           2                 4             60

 

Multiply both sides by   EI6L / w     and the lead term "disappears"

 

0  =   L^2 x^2     -   x^4     -  7L^4

        ______         ____      _____

             2                4            60

 

Multiply through by  - 60

 

15x^4  -  30L^2x^2  +  7L^4   =   0

 

15x^4  -  30L^2x^2     =  -  7L^4         factor  out 15

 

15 ( x^4 - 2L^2x^2)  = - 7L^4            divide both sides  by 15

 

x^4  - 2L^2x^2   =     - 7L^4 / 15

 

Take  1/2  of 2L^2  = L^2

Square this  = L^4

Add to both sides

 

x^4 - 2L^2 x^2  + L^4  =   -7L^4 / 15   + L^4   

 

Factor the left side   and simplify

 

( x^2  - L^2)^2  =   8L^4 / 15

 

Take both roots  and simplify

 

x^2  - L^2  =   ±√ [ (8L^4 / 15) ]

 

x^2 - L^2  =  ±2L^2√ [ 2/15 ]

 

Add L^2  to both sides

 

x^2  =  L^2  ± 2L^2√ [ 2/15 ]

 

Take both roots again

 

x =  ±√ ( L^2 ± 2L^2√ [ 2/15 ]  )  =    ± L√ ( 1 ± 2√ [ 2/15 ]  ) 

 

 

cool cool cool

CPhill  Oct 25, 2018
edited by CPhill  Oct 25, 2018
edited by CPhill  Oct 25, 2018
edited by CPhill  Oct 25, 2018
edited by CPhill  Oct 25, 2018
 #2
avatar
+1

how b****y painful.

 

thank you!

Guest Oct 25, 2018

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