How can I find a limit using equivalent functions and substitutions ( without applying L'Hospital) for the...












-1












$begingroup$


How can I find a limit using equivalent functions and substitutions ( without applying L'Hospital) for the following problem?



There you can see the expression, I need to find the limit for, as x tends to 0



$exp[(cos(sqrt x)-1)/x]$, square brackets for clarity.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Hint: try using the power reduction formula for sine.
    $endgroup$
    – Jordan Green
    Jan 22 at 18:42












  • $begingroup$
    Then it would be $$exp[(sinx)/x]$$ which is one? Could it be the solution of the problem be $$e^1$$?
    $endgroup$
    – Ieva Brakmane
    Jan 22 at 18:54










  • $begingroup$
    Not quite. Note that $frac{ cos(sqrt{x}) - 1}{x} = frac{-2 (sin(sqrt{x}))^2}{x} = -2 (frac{sin(sqrt{x})}{x})^2$.
    $endgroup$
    – Jordan Green
    Jan 22 at 19:01










  • $begingroup$
    now I simplified: $$e^{-frac{2sin ^2left(sqrt{x}right)}{x^2}}$$ Then It I would take the root of x in front of the expression it would fraction with -2 so the solution would be $$e^{-1}$$?
    $endgroup$
    – Ieva Brakmane
    Jan 22 at 19:19












  • $begingroup$
    Sorry, I should have typed $frac{-2(sin(sqrt{x})}{x} = -2 ( frac{sin(sqrt{x})}{sqrt{x}})^2$. What can you say about $frac{sin(sqrt{x})}{sqrt{x}}$ as $x$ tends to $0$ from the right?
    $endgroup$
    – Jordan Green
    Jan 22 at 19:19


















-1












$begingroup$


How can I find a limit using equivalent functions and substitutions ( without applying L'Hospital) for the following problem?



There you can see the expression, I need to find the limit for, as x tends to 0



$exp[(cos(sqrt x)-1)/x]$, square brackets for clarity.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Hint: try using the power reduction formula for sine.
    $endgroup$
    – Jordan Green
    Jan 22 at 18:42












  • $begingroup$
    Then it would be $$exp[(sinx)/x]$$ which is one? Could it be the solution of the problem be $$e^1$$?
    $endgroup$
    – Ieva Brakmane
    Jan 22 at 18:54










  • $begingroup$
    Not quite. Note that $frac{ cos(sqrt{x}) - 1}{x} = frac{-2 (sin(sqrt{x}))^2}{x} = -2 (frac{sin(sqrt{x})}{x})^2$.
    $endgroup$
    – Jordan Green
    Jan 22 at 19:01










  • $begingroup$
    now I simplified: $$e^{-frac{2sin ^2left(sqrt{x}right)}{x^2}}$$ Then It I would take the root of x in front of the expression it would fraction with -2 so the solution would be $$e^{-1}$$?
    $endgroup$
    – Ieva Brakmane
    Jan 22 at 19:19












  • $begingroup$
    Sorry, I should have typed $frac{-2(sin(sqrt{x})}{x} = -2 ( frac{sin(sqrt{x})}{sqrt{x}})^2$. What can you say about $frac{sin(sqrt{x})}{sqrt{x}}$ as $x$ tends to $0$ from the right?
    $endgroup$
    – Jordan Green
    Jan 22 at 19:19
















-1












-1








-1





$begingroup$


How can I find a limit using equivalent functions and substitutions ( without applying L'Hospital) for the following problem?



There you can see the expression, I need to find the limit for, as x tends to 0



$exp[(cos(sqrt x)-1)/x]$, square brackets for clarity.










share|cite|improve this question











$endgroup$




How can I find a limit using equivalent functions and substitutions ( without applying L'Hospital) for the following problem?



There you can see the expression, I need to find the limit for, as x tends to 0



$exp[(cos(sqrt x)-1)/x]$, square brackets for clarity.







limits-without-lhopital






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 23 at 12:47









Namaste

1




1










asked Jan 22 at 18:28









Ieva BrakmaneIeva Brakmane

163




163












  • $begingroup$
    Hint: try using the power reduction formula for sine.
    $endgroup$
    – Jordan Green
    Jan 22 at 18:42












  • $begingroup$
    Then it would be $$exp[(sinx)/x]$$ which is one? Could it be the solution of the problem be $$e^1$$?
    $endgroup$
    – Ieva Brakmane
    Jan 22 at 18:54










  • $begingroup$
    Not quite. Note that $frac{ cos(sqrt{x}) - 1}{x} = frac{-2 (sin(sqrt{x}))^2}{x} = -2 (frac{sin(sqrt{x})}{x})^2$.
    $endgroup$
    – Jordan Green
    Jan 22 at 19:01










  • $begingroup$
    now I simplified: $$e^{-frac{2sin ^2left(sqrt{x}right)}{x^2}}$$ Then It I would take the root of x in front of the expression it would fraction with -2 so the solution would be $$e^{-1}$$?
    $endgroup$
    – Ieva Brakmane
    Jan 22 at 19:19












  • $begingroup$
    Sorry, I should have typed $frac{-2(sin(sqrt{x})}{x} = -2 ( frac{sin(sqrt{x})}{sqrt{x}})^2$. What can you say about $frac{sin(sqrt{x})}{sqrt{x}}$ as $x$ tends to $0$ from the right?
    $endgroup$
    – Jordan Green
    Jan 22 at 19:19




















  • $begingroup$
    Hint: try using the power reduction formula for sine.
    $endgroup$
    – Jordan Green
    Jan 22 at 18:42












  • $begingroup$
    Then it would be $$exp[(sinx)/x]$$ which is one? Could it be the solution of the problem be $$e^1$$?
    $endgroup$
    – Ieva Brakmane
    Jan 22 at 18:54










  • $begingroup$
    Not quite. Note that $frac{ cos(sqrt{x}) - 1}{x} = frac{-2 (sin(sqrt{x}))^2}{x} = -2 (frac{sin(sqrt{x})}{x})^2$.
    $endgroup$
    – Jordan Green
    Jan 22 at 19:01










  • $begingroup$
    now I simplified: $$e^{-frac{2sin ^2left(sqrt{x}right)}{x^2}}$$ Then It I would take the root of x in front of the expression it would fraction with -2 so the solution would be $$e^{-1}$$?
    $endgroup$
    – Ieva Brakmane
    Jan 22 at 19:19












  • $begingroup$
    Sorry, I should have typed $frac{-2(sin(sqrt{x})}{x} = -2 ( frac{sin(sqrt{x})}{sqrt{x}})^2$. What can you say about $frac{sin(sqrt{x})}{sqrt{x}}$ as $x$ tends to $0$ from the right?
    $endgroup$
    – Jordan Green
    Jan 22 at 19:19


















$begingroup$
Hint: try using the power reduction formula for sine.
$endgroup$
– Jordan Green
Jan 22 at 18:42






$begingroup$
Hint: try using the power reduction formula for sine.
$endgroup$
– Jordan Green
Jan 22 at 18:42














$begingroup$
Then it would be $$exp[(sinx)/x]$$ which is one? Could it be the solution of the problem be $$e^1$$?
$endgroup$
– Ieva Brakmane
Jan 22 at 18:54




$begingroup$
Then it would be $$exp[(sinx)/x]$$ which is one? Could it be the solution of the problem be $$e^1$$?
$endgroup$
– Ieva Brakmane
Jan 22 at 18:54












$begingroup$
Not quite. Note that $frac{ cos(sqrt{x}) - 1}{x} = frac{-2 (sin(sqrt{x}))^2}{x} = -2 (frac{sin(sqrt{x})}{x})^2$.
$endgroup$
– Jordan Green
Jan 22 at 19:01




$begingroup$
Not quite. Note that $frac{ cos(sqrt{x}) - 1}{x} = frac{-2 (sin(sqrt{x}))^2}{x} = -2 (frac{sin(sqrt{x})}{x})^2$.
$endgroup$
– Jordan Green
Jan 22 at 19:01












$begingroup$
now I simplified: $$e^{-frac{2sin ^2left(sqrt{x}right)}{x^2}}$$ Then It I would take the root of x in front of the expression it would fraction with -2 so the solution would be $$e^{-1}$$?
$endgroup$
– Ieva Brakmane
Jan 22 at 19:19






$begingroup$
now I simplified: $$e^{-frac{2sin ^2left(sqrt{x}right)}{x^2}}$$ Then It I would take the root of x in front of the expression it would fraction with -2 so the solution would be $$e^{-1}$$?
$endgroup$
– Ieva Brakmane
Jan 22 at 19:19














$begingroup$
Sorry, I should have typed $frac{-2(sin(sqrt{x})}{x} = -2 ( frac{sin(sqrt{x})}{sqrt{x}})^2$. What can you say about $frac{sin(sqrt{x})}{sqrt{x}}$ as $x$ tends to $0$ from the right?
$endgroup$
– Jordan Green
Jan 22 at 19:19






$begingroup$
Sorry, I should have typed $frac{-2(sin(sqrt{x})}{x} = -2 ( frac{sin(sqrt{x})}{sqrt{x}})^2$. What can you say about $frac{sin(sqrt{x})}{sqrt{x}}$ as $x$ tends to $0$ from the right?
$endgroup$
– Jordan Green
Jan 22 at 19:19












1 Answer
1






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0












$begingroup$

You may set $x = t^2$ and use





  • $lim_{yto 0}frac{1-cos y}{y^2} = frac{1}{2}$ (easy to verify with L'Hospital).


begin{eqnarray*} e^{frac{cossqrt x -1}{x}}
& = & e^{frac{cos t -1}{t^2}}\
& stackrel{tto 0}{longrightarrow} & e^{-frac{1}{2}} =frac{1}{sqrt{e}}\
end{eqnarray*}






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    1 Answer
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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    0












    $begingroup$

    You may set $x = t^2$ and use





    • $lim_{yto 0}frac{1-cos y}{y^2} = frac{1}{2}$ (easy to verify with L'Hospital).


    begin{eqnarray*} e^{frac{cossqrt x -1}{x}}
    & = & e^{frac{cos t -1}{t^2}}\
    & stackrel{tto 0}{longrightarrow} & e^{-frac{1}{2}} =frac{1}{sqrt{e}}\
    end{eqnarray*}






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      You may set $x = t^2$ and use





      • $lim_{yto 0}frac{1-cos y}{y^2} = frac{1}{2}$ (easy to verify with L'Hospital).


      begin{eqnarray*} e^{frac{cossqrt x -1}{x}}
      & = & e^{frac{cos t -1}{t^2}}\
      & stackrel{tto 0}{longrightarrow} & e^{-frac{1}{2}} =frac{1}{sqrt{e}}\
      end{eqnarray*}






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        You may set $x = t^2$ and use





        • $lim_{yto 0}frac{1-cos y}{y^2} = frac{1}{2}$ (easy to verify with L'Hospital).


        begin{eqnarray*} e^{frac{cossqrt x -1}{x}}
        & = & e^{frac{cos t -1}{t^2}}\
        & stackrel{tto 0}{longrightarrow} & e^{-frac{1}{2}} =frac{1}{sqrt{e}}\
        end{eqnarray*}






        share|cite|improve this answer









        $endgroup$



        You may set $x = t^2$ and use





        • $lim_{yto 0}frac{1-cos y}{y^2} = frac{1}{2}$ (easy to verify with L'Hospital).


        begin{eqnarray*} e^{frac{cossqrt x -1}{x}}
        & = & e^{frac{cos t -1}{t^2}}\
        & stackrel{tto 0}{longrightarrow} & e^{-frac{1}{2}} =frac{1}{sqrt{e}}\
        end{eqnarray*}







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 23 at 12:03









        trancelocationtrancelocation

        12.6k1826




        12.6k1826






























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