We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website. cookie policy and privacy policy.

+0

# solve for x

0
192
2

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!

Oct 25, 2018

### 2+0 Answers

#1
+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 ]  )   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
+1

how b****y painful.

thank you!

Oct 25, 2018