No LIMITs to the amount of limit problems!

Calculus Level 2

Evaluate lim x 0 1 7 x 1 x \large \lim\limits_{x\to 0}\frac{17^x - 1}{x} If this limit does not exist, put 1 -1 as your answer.


The answer is 2.83321334406.

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2 solutions

James Watson
Sep 2, 2020

Since plugging in 0 0 here gives us a 0 0 \cfrac{0}{0} indeterminate form, we can use L'Hopital's Rule and differentiate the top and the bottom of the fraction in the limit: lim x 0 1 7 x 1 x lim x 0 d d x ( 1 7 x 1 ) d d x ( x ) = lim x 0 1 7 x ln ( 17 ) 1 = lim x 0 1 7 x ln ( 17 ) = 1 7 0 ln ( 17 ) = ln ( 17 ) = 2.83321334406 \begin{aligned} \lim\limits_{x\to 0} \frac{17^x - 1}{x} \implies \lim\limits_{x\to 0} \frac{\frac{d}{dx}(17^x - 1)}{\frac{d}{dx}(x)} &= \lim\limits_{x\to 0} \frac{17^x \ln(17) }{1} \\ &= \lim\limits_{x\to 0} 17^x \ln(17) \\ &= 17^0 \ln(17) = \green{\boxed{\ln(17)}} = \green{\boxed{2.83321334406\dots}}\end{aligned}

I forgot about L'Hopital's rule

Lâm Lê - 9 months, 1 week ago
Krishna Karthik
Sep 3, 2020

This is your classical L'Hôpital problem; differentiating both top and bottom will result in:

d d x 1 7 x = ln ( 17 ) 1 7 x \displaystyle \frac{d}{dx}17^x = \ln(17) 17^x

d d x x = 1 \displaystyle \frac{d}{dx}x = 1

Plug in zero to the numerator, we get:

ln ( 17 ) \boxed{\ln(17)}

Thanks for the helpful solution, it's a very funny problem to do

Bilu Bilu - 9 months, 1 week ago

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