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Question Number 9875 by j.masanja06@gmail.com last updated on 11/Jan/17
solve the value of x.  5logx=(x/4)
solvethevalueofx.5logx=x4
Answered by mrW1 last updated on 12/Jan/17
5log x=(x/4)  log x=(x/(20))  ((ln x)/(ln 10))=(x/(20))  ln x=((ln 10)/(20))x  with a=−((ln 10)/(20))≈−0.115129  ln x=−ax  x=e^(−ax) =(1/e^(ax) )  xe^(ax) =1  (ax)e^(ax) =a  ⇒ax=W(a)  with W=Lambert W function  x=((W(a))/a)=((W(−((ln 10)/(20))))/(−((ln 10)/(20))))≈((W(−0.115129))/(−0.115129))  ≈((−0.13128)/(−0.115129))≈1.140286  or  ≈((−3.3794)/(−0.115128))≈29.35316
5logx=x4logx=x20lnxln10=x20lnx=ln1020xwitha=ln10200.115129lnx=axx=eax=1eaxxeax=1(ax)eax=aax=W(a)withW=LambertWfunctionx=W(a)a=W(ln1020)ln1020W(0.115129)0.1151290.131280.1151291.140286or3.37940.11512829.35316

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