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Question-139771




Question Number 139771 by Engr_Jidda last updated on 01/May/21
Commented by mohammad17 last updated on 01/May/21
yes sir realy im sory can you solve this?
$${yes}\:{sir}\:{realy}\:{im}\:{sory}\:{can}\:{you}\:{solve}\:{this}? \\ $$
Commented by mr W last updated on 01/May/21
take care!  (3)^(1/(1/2)) =3^2 ≠3^(1/2)
$${take}\:{care}! \\ $$$$\sqrt[{\frac{\mathrm{1}}{\mathrm{2}}}]{\mathrm{3}}=\mathrm{3}^{\mathrm{2}} \neq\mathrm{3}^{\frac{\mathrm{1}}{\mathrm{2}}} \\ $$
Commented by mohammad17 last updated on 01/May/21
sir if (3)^(1/(1/2)) =3^2  then (3)^(1/(1/7)) =3^7 its right or no
$${sir}\:{if}\:\sqrt[{\frac{\mathrm{1}}{\mathrm{2}}}]{\mathrm{3}}=\mathrm{3}^{\mathrm{2}} \:{then}\:\sqrt[{\frac{\mathrm{1}}{\mathrm{7}}}]{\mathrm{3}}=\mathrm{3}^{\mathrm{7}} {its}\:{right}\:{or}\:{no} \\ $$
Commented by mr W last updated on 01/May/21
yes. it′s right.
$${yes}.\:{it}'{s}\:{right}. \\ $$
Commented by mohammad17 last updated on 01/May/21
thank you very much sir
$${thank}\:{you}\:{very}\:{much}\:{sir}\: \\ $$
Answered by mr W last updated on 01/May/21
(a)^(1/x) =a^(1/x)   ⇒(a)^(1/(1/x)) =a^(1/(((1/x)))) =a^x     ((((x^x )^(1/(1/x)) )^x ))^(1/(1/x)) =4  (((x^x^2  )^x ))^(1/(1/x)) =4  (x^x^2  )^x^2  =4  x^(x^2 x^2 ) =4  x^x^4  =4  ⇒x^4 =4  ⇒x=±(4)^(1/4) =±(√2)
$$\sqrt[{{x}}]{{a}}={a}^{\frac{\mathrm{1}}{{x}}} \\ $$$$\Rightarrow\sqrt[{\frac{\mathrm{1}}{{x}}}]{{a}}={a}^{\frac{\mathrm{1}}{\left(\frac{\mathrm{1}}{{x}}\right)}} ={a}^{{x}} \\ $$$$ \\ $$$$\sqrt[{\frac{\mathrm{1}}{{x}}}]{\left(\sqrt[{\frac{\mathrm{1}}{{x}}}]{{x}^{{x}} }\right)^{{x}} }=\mathrm{4} \\ $$$$\sqrt[{\frac{\mathrm{1}}{{x}}}]{\left({x}^{{x}^{\mathrm{2}} } \right)^{{x}} }=\mathrm{4} \\ $$$$\left({x}^{{x}^{\mathrm{2}} } \right)^{{x}^{\mathrm{2}} } =\mathrm{4} \\ $$$${x}^{{x}^{\mathrm{2}} {x}^{\mathrm{2}} } =\mathrm{4} \\ $$$${x}^{{x}^{\mathrm{4}} } =\mathrm{4} \\ $$$$\Rightarrow{x}^{\mathrm{4}} =\mathrm{4} \\ $$$$\Rightarrow{x}=\pm\sqrt[{\mathrm{4}}]{\mathrm{4}}=\pm\sqrt{\mathrm{2}} \\ $$
Commented by Ankushkumarparcha last updated on 01/May/21
if u use power tower then this equation has no solution  ∵ range R ∈ [(1/e) , e]
$${if}\:{u}\:{use}\:{power}\:{tower}\:{then}\:{this}\:{equation}\:{has}\:{no}\:{solution} \\ $$$$\because\:{range}\:{R}\:\in\:\left[\frac{\mathrm{1}}{{e}}\:,\:{e}\right] \\ $$
Commented by mr W last updated on 01/May/21
i didn′t use power tower.  the original equation is equivalent to  x^x^4  =4.  and eqn. x^x^4  =a has always solution if  a≥≈0.9121
$${i}\:{didn}'{t}\:{use}\:{power}\:{tower}. \\ $$$${the}\:{original}\:{equation}\:{is}\:{equivalent}\:{to} \\ $$$${x}^{{x}^{\mathrm{4}} } =\mathrm{4}. \\ $$$${and}\:{eqn}.\:{x}^{{x}^{\mathrm{4}} } ={a}\:{has}\:{always}\:{solution}\:{if} \\ $$$${a}\geqslant\approx\mathrm{0}.\mathrm{9121} \\ $$
Answered by Ankushkumarparcha last updated on 01/May/21
Solution: ((((x^x )^(1/(1/x)) )^x ))^(1/(1/x))  = 4 => x^x^4   = 4   (∵  (b)^(1/(1/a))  = b^a )  By observing we get, x = (√2)
$${Solution}:\:\sqrt[{\frac{\mathrm{1}}{{x}}}]{\left(\sqrt[{\frac{\mathrm{1}}{{x}}}]{{x}^{{x}} }\right)^{{x}} }\:=\:\mathrm{4}\:=>\:{x}^{{x}^{\mathrm{4}} } \:=\:\mathrm{4}\:\:\:\left(\because\:\:\sqrt[{\frac{\mathrm{1}}{{a}}}]{{b}}\:=\:{b}^{{a}} \right) \\ $$$${By}\:{observing}\:{we}\:{get},\:{x}\:=\:\sqrt{\mathrm{2}}\: \\ $$$$ \\ $$
Commented by mr W last updated on 01/May/21
x=−(√2) is also solution.
$${x}=−\sqrt{\mathrm{2}}\:{is}\:{also}\:{solution}. \\ $$
Answered by Ar Brandon last updated on 01/May/21
x^x^4  =4⇒x^4 lnx=ln4  ⇒4x^4 lnx=4ln4  ⇒4lnx∙e^(4lnx) =ln4∙e^(ln4)   ⇒W_0 (4lnx)=W_0 (ln4)  ⇒4lnx=ln4⇒x^4 =4⇒x=±(√2)
$$\mathrm{x}^{\mathrm{x}^{\mathrm{4}} } =\mathrm{4}\Rightarrow\mathrm{x}^{\mathrm{4}} \mathrm{lnx}=\mathrm{ln4} \\ $$$$\Rightarrow\mathrm{4x}^{\mathrm{4}} \mathrm{lnx}=\mathrm{4ln4} \\ $$$$\Rightarrow\mathrm{4lnx}\centerdot\mathrm{e}^{\mathrm{4lnx}} =\mathrm{ln4}\centerdot\mathrm{e}^{\mathrm{ln4}} \\ $$$$\Rightarrow\mathrm{W}_{\mathrm{0}} \left(\mathrm{4lnx}\right)=\mathrm{W}_{\mathrm{0}} \left(\mathrm{ln4}\right) \\ $$$$\Rightarrow\mathrm{4lnx}=\mathrm{ln4}\Rightarrow\mathrm{x}^{\mathrm{4}} =\mathrm{4}\Rightarrow\mathrm{x}=\pm\sqrt{\mathrm{2}} \\ $$

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