Verifying the limit of the expressions

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I have calculated the limit of the following expressions as follows:



$$lim_x rightarrow 0 fracx times frac2x5x + 3 + e^-2x = lim_x rightarrow 0 frac2x5x^2 + 3x + xe^-2x = lim_x rightarrow 0 frac210x + 3 + e^-2x -2xe^-2x (textusing Le Chatelier's principle) = frac23+1$$



$$lim_x rightarrow 0 fracx times frac2x4 + frac1-x1+x = lim_x rightarrow 0 frac2x(1+x)4x(1+x) + x(1-x) = lim_x rightarrow 0 frac2x(1+x)5x-3x^2 = lim_x rightarrow 0 frac4x+25 - 6x (textusing Le Chatelier's principle) = frac25$$



Are my calculations correct?







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  • 2




    Yes, but why didn't you just simplify the numerators?
    – Bernard
    Jul 18 at 20:01










  • @Eval Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
    – gimusi
    Aug 8 at 23:05














up vote
1
down vote

favorite
2












I have calculated the limit of the following expressions as follows:



$$lim_x rightarrow 0 fracx times frac2x5x + 3 + e^-2x = lim_x rightarrow 0 frac2x5x^2 + 3x + xe^-2x = lim_x rightarrow 0 frac210x + 3 + e^-2x -2xe^-2x (textusing Le Chatelier's principle) = frac23+1$$



$$lim_x rightarrow 0 fracx times frac2x4 + frac1-x1+x = lim_x rightarrow 0 frac2x(1+x)4x(1+x) + x(1-x) = lim_x rightarrow 0 frac2x(1+x)5x-3x^2 = lim_x rightarrow 0 frac4x+25 - 6x (textusing Le Chatelier's principle) = frac25$$



Are my calculations correct?







share|cite|improve this question

















  • 2




    Yes, but why didn't you just simplify the numerators?
    – Bernard
    Jul 18 at 20:01










  • @Eval Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
    – gimusi
    Aug 8 at 23:05












up vote
1
down vote

favorite
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up vote
1
down vote

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I have calculated the limit of the following expressions as follows:



$$lim_x rightarrow 0 fracx times frac2x5x + 3 + e^-2x = lim_x rightarrow 0 frac2x5x^2 + 3x + xe^-2x = lim_x rightarrow 0 frac210x + 3 + e^-2x -2xe^-2x (textusing Le Chatelier's principle) = frac23+1$$



$$lim_x rightarrow 0 fracx times frac2x4 + frac1-x1+x = lim_x rightarrow 0 frac2x(1+x)4x(1+x) + x(1-x) = lim_x rightarrow 0 frac2x(1+x)5x-3x^2 = lim_x rightarrow 0 frac4x+25 - 6x (textusing Le Chatelier's principle) = frac25$$



Are my calculations correct?







share|cite|improve this question













I have calculated the limit of the following expressions as follows:



$$lim_x rightarrow 0 fracx times frac2x5x + 3 + e^-2x = lim_x rightarrow 0 frac2x5x^2 + 3x + xe^-2x = lim_x rightarrow 0 frac210x + 3 + e^-2x -2xe^-2x (textusing Le Chatelier's principle) = frac23+1$$



$$lim_x rightarrow 0 fracx times frac2x4 + frac1-x1+x = lim_x rightarrow 0 frac2x(1+x)4x(1+x) + x(1-x) = lim_x rightarrow 0 frac2x(1+x)5x-3x^2 = lim_x rightarrow 0 frac4x+25 - 6x (textusing Le Chatelier's principle) = frac25$$



Are my calculations correct?









share|cite|improve this question












share|cite|improve this question




share|cite|improve this question








edited Jul 18 at 20:08
























asked Jul 18 at 19:58









Eval

17810




17810







  • 2




    Yes, but why didn't you just simplify the numerators?
    – Bernard
    Jul 18 at 20:01










  • @Eval Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
    – gimusi
    Aug 8 at 23:05












  • 2




    Yes, but why didn't you just simplify the numerators?
    – Bernard
    Jul 18 at 20:01










  • @Eval Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
    – gimusi
    Aug 8 at 23:05







2




2




Yes, but why didn't you just simplify the numerators?
– Bernard
Jul 18 at 20:01




Yes, but why didn't you just simplify the numerators?
– Bernard
Jul 18 at 20:01












@Eval Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
– gimusi
Aug 8 at 23:05




@Eval Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
– gimusi
Aug 8 at 23:05










1 Answer
1






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oldest

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up vote
1
down vote



accepted










As suggested by Bernard in the above comment, more simply we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx5x + 3 + e^-2x = lim_x rightarrow 0 frac25x + 3 + e^-2x stackreltextby continuity= frac23+1=frac12$$



and similarly for the second we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx4 + frac1-x1+x =lim_x rightarrow 0 frac24 + frac1-x1+x stackreltextby continuity= frac24+1=frac25$$



Refer also to: Why are we allowed to cancel fractions in limits?






share|cite|improve this answer























  • We can cancel out x in the numerator and the denominator. Right?
    – Eval
    Jul 18 at 20:10










  • Yes of course, I've highlighted that in red.
    – gimusi
    Jul 18 at 20:11











  • Will the solution still be correct if x is a complex number?
    – Eval
    Jul 18 at 20:13










  • @Eval Yes in this case the solution should be the same, indeed we can simplify in teh same way and $5zto 0$, $e^-2z=e^-2xe^-2iyto1$, $frac1-z1+zto 1$.
    – gimusi
    Jul 18 at 20:25










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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
1
down vote



accepted










As suggested by Bernard in the above comment, more simply we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx5x + 3 + e^-2x = lim_x rightarrow 0 frac25x + 3 + e^-2x stackreltextby continuity= frac23+1=frac12$$



and similarly for the second we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx4 + frac1-x1+x =lim_x rightarrow 0 frac24 + frac1-x1+x stackreltextby continuity= frac24+1=frac25$$



Refer also to: Why are we allowed to cancel fractions in limits?






share|cite|improve this answer























  • We can cancel out x in the numerator and the denominator. Right?
    – Eval
    Jul 18 at 20:10










  • Yes of course, I've highlighted that in red.
    – gimusi
    Jul 18 at 20:11











  • Will the solution still be correct if x is a complex number?
    – Eval
    Jul 18 at 20:13










  • @Eval Yes in this case the solution should be the same, indeed we can simplify in teh same way and $5zto 0$, $e^-2z=e^-2xe^-2iyto1$, $frac1-z1+zto 1$.
    – gimusi
    Jul 18 at 20:25














up vote
1
down vote



accepted










As suggested by Bernard in the above comment, more simply we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx5x + 3 + e^-2x = lim_x rightarrow 0 frac25x + 3 + e^-2x stackreltextby continuity= frac23+1=frac12$$



and similarly for the second we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx4 + frac1-x1+x =lim_x rightarrow 0 frac24 + frac1-x1+x stackreltextby continuity= frac24+1=frac25$$



Refer also to: Why are we allowed to cancel fractions in limits?






share|cite|improve this answer























  • We can cancel out x in the numerator and the denominator. Right?
    – Eval
    Jul 18 at 20:10










  • Yes of course, I've highlighted that in red.
    – gimusi
    Jul 18 at 20:11











  • Will the solution still be correct if x is a complex number?
    – Eval
    Jul 18 at 20:13










  • @Eval Yes in this case the solution should be the same, indeed we can simplify in teh same way and $5zto 0$, $e^-2z=e^-2xe^-2iyto1$, $frac1-z1+zto 1$.
    – gimusi
    Jul 18 at 20:25












up vote
1
down vote



accepted







up vote
1
down vote



accepted






As suggested by Bernard in the above comment, more simply we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx5x + 3 + e^-2x = lim_x rightarrow 0 frac25x + 3 + e^-2x stackreltextby continuity= frac23+1=frac12$$



and similarly for the second we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx4 + frac1-x1+x =lim_x rightarrow 0 frac24 + frac1-x1+x stackreltextby continuity= frac24+1=frac25$$



Refer also to: Why are we allowed to cancel fractions in limits?






share|cite|improve this answer















As suggested by Bernard in the above comment, more simply we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx5x + 3 + e^-2x = lim_x rightarrow 0 frac25x + 3 + e^-2x stackreltextby continuity= frac23+1=frac12$$



and similarly for the second we have



$$lim_x rightarrow 0 fraccolorredx times frac2colorredx4 + frac1-x1+x =lim_x rightarrow 0 frac24 + frac1-x1+x stackreltextby continuity= frac24+1=frac25$$



Refer also to: Why are we allowed to cancel fractions in limits?







share|cite|improve this answer















share|cite|improve this answer



share|cite|improve this answer








edited Jul 18 at 20:11


























answered Jul 18 at 20:07









gimusi

65.4k73584




65.4k73584











  • We can cancel out x in the numerator and the denominator. Right?
    – Eval
    Jul 18 at 20:10










  • Yes of course, I've highlighted that in red.
    – gimusi
    Jul 18 at 20:11











  • Will the solution still be correct if x is a complex number?
    – Eval
    Jul 18 at 20:13










  • @Eval Yes in this case the solution should be the same, indeed we can simplify in teh same way and $5zto 0$, $e^-2z=e^-2xe^-2iyto1$, $frac1-z1+zto 1$.
    – gimusi
    Jul 18 at 20:25
















  • We can cancel out x in the numerator and the denominator. Right?
    – Eval
    Jul 18 at 20:10










  • Yes of course, I've highlighted that in red.
    – gimusi
    Jul 18 at 20:11











  • Will the solution still be correct if x is a complex number?
    – Eval
    Jul 18 at 20:13










  • @Eval Yes in this case the solution should be the same, indeed we can simplify in teh same way and $5zto 0$, $e^-2z=e^-2xe^-2iyto1$, $frac1-z1+zto 1$.
    – gimusi
    Jul 18 at 20:25















We can cancel out x in the numerator and the denominator. Right?
– Eval
Jul 18 at 20:10




We can cancel out x in the numerator and the denominator. Right?
– Eval
Jul 18 at 20:10












Yes of course, I've highlighted that in red.
– gimusi
Jul 18 at 20:11





Yes of course, I've highlighted that in red.
– gimusi
Jul 18 at 20:11













Will the solution still be correct if x is a complex number?
– Eval
Jul 18 at 20:13




Will the solution still be correct if x is a complex number?
– Eval
Jul 18 at 20:13












@Eval Yes in this case the solution should be the same, indeed we can simplify in teh same way and $5zto 0$, $e^-2z=e^-2xe^-2iyto1$, $frac1-z1+zto 1$.
– gimusi
Jul 18 at 20:25




@Eval Yes in this case the solution should be the same, indeed we can simplify in teh same way and $5zto 0$, $e^-2z=e^-2xe^-2iyto1$, $frac1-z1+zto 1$.
– gimusi
Jul 18 at 20:25












 

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