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Mathematics 18 Online
OpenStudy (anonymous):

ln(-5x+3)=ln2x+2

OpenStudy (anonymous):

Do I cancel out the ln's?

OpenStudy (anonymous):

@hartnn

hartnn (hartnn):

whats the question ? \(\ln (-5x+3)=\ln 2x+2\) or \(\ln (-5x+3)=\ln (2x+2)\) ?

OpenStudy (anonymous):

The top one

hartnn (hartnn):

then you cannot cancel and its not an easy Q

OpenStudy (anonymous):

Then what do you do?

hartnn (hartnn):

i would use these 2, \(\ln A=B \implies A=e^B\) and \(\large e^{\ln A}=A\)

hartnn (hartnn):

first, \(\huge (-5x+3)=e^{\ln 2x+2}\) got this ?

OpenStudy (anonymous):

One quick question, would you treat ln like log?

hartnn (hartnn):

yes, ln is log only, but with different base log --->base = 10 ln ----> base = e all properties of log applies to both

OpenStudy (anonymous):

Would there be another way to write the first step?

hartnn (hartnn):

i can't think of other...i already said this wasn't going to be easy...and complications haven't even started yet :P

OpenStudy (anonymous):

Haha, alright

hartnn (hartnn):

let me put down steps to let u know \(\huge (-5x+3)=e^{\ln 2x}\times e^2 \\ -5x+3 = 2x (e^2) \\ x (2e^2 +5)=3 \\ x= \dfrac{3}{2e^2+5}\) all these just because there were no brackets on right side... :P

hartnn (hartnn):

if there were brackets on right side, then u could have cancelled ln and it would be as simple as -5x+3=2x+2

hartnn (hartnn):

any doubts ?

OpenStudy (anonymous):

I'll try to process that in my brain :P

hartnn (hartnn):

okk. i got to go, bye :)

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