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Mathematics 7 Online
OpenStudy (anonymous):

How do you apply ln and e?

OpenStudy (anonymous):

Example?

OpenStudy (anonymous):

ln(2) = 0.693 e^0.693 = 2

OpenStudy (anonymous):

My example is e^x+5/e^5=3 and I have to work it out but didn't know what e equalled. Thank you!!!

OpenStudy (anonymous):

Well, 5/e^5 = 0.0337 so you want x = ln(3 - 0.0337)

OpenStudy (lgbasallote):

actually....there's a simpler way..

OpenStudy (lgbasallote):

\[\huge \frac{e^{x+5}}{e^5} \implies e^{x + 5 - 5}\] do you agree? @calchelp101 ? this is algebra..

OpenStudy (anonymous):

Thank you! So would it now be e^x because it would cancel?

OpenStudy (anonymous):

sorry of course e^x+5/e^5= e^x

OpenStudy (lgbasallote):

yup

OpenStudy (lgbasallote):

so \[\huge e^x = 3\] now use ln

OpenStudy (anonymous):

You both are the best! Thank you so much! If you don't mind, can I ask one more question: I now have e^x=3 Should it be left like that or multiply 3 by 1/x?

OpenStudy (anonymous):

Oh, okay! Thanks!

OpenStudy (lgbasallote):

haha =)) guess that was answered quick

OpenStudy (anonymous):

does ln cancel e?

OpenStudy (lgbasallote):

yup

OpenStudy (lgbasallote):

...well it depends on what you mean

OpenStudy (lgbasallote):

can you show me what you're attempting to do?

OpenStudy (anonymous):

Sure. I have e^x=3 so would I have x=3(ln) after applying?

OpenStudy (anonymous):

So x=1.0986?

OpenStudy (lgbasallote):

x = ln (3) haha

OpenStudy (lgbasallote):

did they tell you to give exact value?

OpenStudy (anonymous):

They didn't specify so I was going to give both.

OpenStudy (lgbasallote):

oh i see...that value is right

OpenStudy (anonymous):

Thank you so much! You are a lifesaver!

OpenStudy (lgbasallote):

haha welcome ^_^

OpenStudy (anonymous):

Only if you have time, I have another ln problem that has been giving me trouble!

OpenStudy (lgbasallote):

sure

OpenStudy (lgbasallote):

what's the problem?

OpenStudy (anonymous):

ln(2x^6+3 square roots of x+8/(x-1)^4)

OpenStudy (lgbasallote):

\[\huge \ln \left(\frac{2x^6 + 3\sqrt{x+8}}{(x-1)^4} \right)\] is this the problem?

OpenStudy (anonymous):

Yes

OpenStudy (lgbasallote):

and you're supposed to.....expand it?

OpenStudy (anonymous):

Yes and simplify

OpenStudy (lgbasallote):

if i were you i'll start with quotient law first

OpenStudy (anonymous):

So after I expand (x-1)^4 what should I do with the 3square roots of x+8?

OpenStudy (lgbasallote):

nothing :D

OpenStudy (lgbasallote):

there is no expansion for \[\ln (a+b)\]

OpenStudy (anonymous):

Oh. Okay. On the bottom I have x^4-4x^3+8x^2-8x+4

OpenStudy (lgbasallote):

well...not exactly...

OpenStudy (lgbasallote):

this is not what i meant by expand...

OpenStudy (anonymous):

You meant expand the ln?

OpenStudy (lgbasallote):

lol that's the objective isnt it?

OpenStudy (anonymous):

Well yes. haha

OpenStudy (lgbasallote):

so expand the ln

OpenStudy (lgbasallote):

use quotient law first

OpenStudy (anonymous):

Okay, great! Thank you so much for your help!

OpenStudy (lgbasallote):

welcome ^_^

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