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Mathematics 20 Online
OpenStudy (anonymous):

Infinite limits with exponential functions.

OpenStudy (anonymous):

\[\frac{ 1-e^x }{ 1+2e^x }\]

OpenStudy (anonymous):

lim x-> inf

OpenStudy (anonymous):

divide numerator and denominator by e^x

OpenStudy (anonymous):

what do you get ?

OpenStudy (anonymous):

ok, so i know when e^x x-> inf, that it = inifinity

OpenStudy (anonymous):

take out e^x as a common factor in both numerator and denominator..

OpenStudy (anonymous):

?

OpenStudy (anonymous):

that will give me a 0 in the num

OpenStudy (anonymous):

\[\frac{ 1-\infty }{ 1+2(\infty )}\]

OpenStudy (anonymous):

\[\frac{ \frac{ 1 }{ e^x } - \frac{ e^x }{ e^x }}{ \frac{ 1 }{ e^x } + \frac{ 2e^x }{ e } }\]

OpenStudy (anonymous):

if you divide numerator and denominator by e^x this is what you get .

OpenStudy (anonymous):

so multiply top and bottom 1/e^x

OpenStudy (anonymous):

\[\frac{ \frac{ 1 }{ e^x } - 1 }{ \frac{ 1 }{ e^x } + 2 }\]

OpenStudy (anonymous):

after simplifying this what you have.. so what is the limit now ?

OpenStudy (anonymous):

hang on not sure how to simplify that

OpenStudy (anonymous):

what i wrote there is after the simplification of the division of num and denom by e^x..

OpenStudy (anonymous):

ya, not sure how to get rid of 1/e^x

OpenStudy (anonymous):

1/e^x = 1/infinty = 0 as limit tends to infinty

OpenStudy (anonymous):

ahhhhh!

OpenStudy (anonymous):

thanks @AbhimanyuPudi

OpenStudy (anonymous):

just as 1/x = zero

OpenStudy (anonymous):

wouldn't you use the Powers rule? \[\frac{ (1-e^x) }{ (1+2e^x) }\] e^x has the power of 1 on the top 2e^x has the power of 2 on the bottom The answer is 1/2

OpenStudy (anonymous):

its -1/2

OpenStudy (anonymous):

yeah that lol

OpenStudy (anonymous):

-0.5 indeed

OpenStudy (anonymous):

welcome @Calle87

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