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Need help with small calculus/math problem

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MikBok117

Hi, I know this isn't the right place, but I'm desprate, the final is in 3 days so... maybe some one can help me.

I have solved problems with L’Hopital’s Rule before, but this one is giving me a headache... Here it is: http://i.imgur.com/1Fje85j.png
I know that first you need to ln (log) it so you can get the x2+2x-3 upfront and then you find the derivative till it is not longer 0/0 or inf/inf, but I am doing all that and still can't find solution. If someone can solved it I would really appreciate it.

Thank you

10 years ago

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8 Comments
agitoliu

(x2+2x-3)ln(x1/2-1) =(x+3)(x-1)ln(x1/2-1) let's see lim (x-1)ln(x1/2-1)=lim ln(x1/2-1)/(1/x-1) using the Rule you'll get it

10 years ago
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MikBok117

Thank you for the answer, tried it still getting 0/0 or inf dont get 1 (as it says on WolframAlpha) or whatever the right answer it is :(

10 years ago
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agitoliu

you'll get 0 if you use the Rule on lim ln(x1/2-1)/(1/x-1) and by e0=1 the right answer is 1.

10 years ago
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MikBok117

How many times i have to use the rule (derivative it) on ln(x1/2-1)/(1/x-1) to get 0 ?

10 years ago
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agitoliu

Just once, you should get (x-1)2 / (x1/2)(x1/2-1)=(x-1)(x1/2+1)/ (x1/2)

10 years ago
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MikBok117

Got it, thank you so much for your time.

10 years ago
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trall111

You can always use WolframAlpha for any math related problem. Helped me quite a bit.

10 years ago
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MikBok117

Yes, tried it, but only the final answer and it says 1 but can't get 1 when im trying to solve it. :/

10 years ago
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Closed 10 years ago by MikBok117.