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Mathematics 7 Online
OpenStudy (anonymous):

what the limit as x goes to infinity of the function ----xln(1-(10/x))????

OpenStudy (anonymous):

Take it by parts what is x as x goes to infinity?

OpenStudy (anonymous):

0

OpenStudy (anonymous):

or 1

OpenStudy (anonymous):

try again infinity, next part on the inside what happens when 10 or any number is over infinity?

OpenStudy (anonymous):

o ya i see x goes to infinity, um its infinity? thats what your asking ?

OpenStudy (anonymous):

Yeah x goes to infinity, that is the first which is then multiplied by len (1-10/x). What happens when 10 or any number is over x as x goes to infinity?

OpenStudy (anonymous):

x gets smaller?

OpenStudy (anonymous):

No, just like earlier x goes to infinity. But the point is it is 10/x. Anytime a number is over infinity it goes to zero. There is a lot of situations in this problem that occurs a lot so you should take notes. That's not the complete answer yet. Let me know if what I am saying makes any sense.

OpenStudy (anonymous):

yes it maks sense ... i know what you were asking now ...

OpenStudy (anonymous):

So you have the first x going to infinity and that is multiplied by ln (1-0). What is ln 0?

OpenStudy (anonymous):

I'm sorry ln 1

OpenStudy (anonymous):

0?

OpenStudy (anonymous):

Right so, if you are keeping tracking you have the lim of infinity times zero. That is a special condition. Check your classroom notes: what to do?

OpenStudy (anonymous):

lhospital rule?

OpenStudy (anonymous):

Right on apply l'hopital to the original equation.

OpenStudy (anonymous):

see im having trouble that part

OpenStudy (anonymous):

i sec

OpenStudy (anonymous):

yeah, product rule u'v+uv'

OpenStudy (anonymous):

ya i get (x/(1-10/x))+ln(1-(10/x))....

OpenStudy (anonymous):

Yeah, you might be off one piece ln (1-10/x) + (10x^3)/(1-10/x)

OpenStudy (anonymous):

Ok, find lim, you found already that ln (1-10/x) goes to zero so just concentrate on last part

OpenStudy (anonymous):

You also found that (1-10/x) goes to 1-0 which is 1. So just find lim 10x^3

OpenStudy (anonymous):

how did you get 10x^3??

OpenStudy (anonymous):

how did you get 10x^3??

OpenStudy (anonymous):

Product rule u is x, u' is 1; v is ln (1-10/x), v' (10x^2)/(1-10/x) Put it together u'v +uv' is ln (1-10/x) + (x10x^2)/(1-10/x) -->ignore everything as stated earlier and the last part is x10^2 --> 10^3

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