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Mathematics 11 Online
OpenStudy (rabya!):

ln(x-3)-ln x=1.5

OpenStudy (rabya!):

i need to find the value of x

Parth (parthkohli):

Your first step would be to simplify the LHS as follows:\[\ln(x - 3) - \ln(x) = \ln \left(\dfrac{x - 3}{x}\right)\]

OpenStudy (rabya!):

YEs after it ?

Parth (parthkohli):

Do you know how to remove \(\ln\) from both sides? Raise both sides to the power \(e\).

OpenStudy (rabya!):

Yes , i tried to solve this sum , and did it half nd then im stuck .. I did it this way , ln(x-3)/x=1.5 ln(x-3)=1.5x ln-3=1.5x-x ln-3=0.5x and now i dont knw wat to do !!

Parth (parthkohli):

Hmm, you have to raise both sides to the power of \(e\) because \(\large \frac{x-3}{x}\) is enclosed within \(\ln\).\[\ln\left(\dfrac{x-3}{x}\right) = 1.5\]\[\dfrac{x-3}{x} = e^{1.5}\]

Parth (parthkohli):

Do you see how and why I did that?

OpenStudy (rabya!):

Yes I understand , wat after it ?

Parth (parthkohli):

\[\dfrac{x -3}{x}=e^{1.5}\]\[x -3 = e^{1.5}x\]\[x - e^{1.5 }x = 3\]\[x(1 - e^{1.5}) = 3\]\[x = \dfrac{3}{1 - e^{1.5}}\]

OpenStudy (rabya!):

and then ?

Parth (parthkohli):

Isn't that it?

OpenStudy (rabya!):

no, I need to find out the value of X

Parth (parthkohli):

That's the value of \(x\).

OpenStudy (rabya!):

Ans. should b -0.861

Parth (parthkohli):

\[\dfrac{3}{1 - e^{1.5}}\]plug this in to your calculator.

OpenStudy (rabya!):

oh wow , I got the answer , Thanku so much !!

Parth (parthkohli):

No problem :)

OpenStudy (rabya!):

2lnx4-lnx2 = 12 .

Parth (parthkohli):

What have you tried?

OpenStudy (rabya!):

yes ! lnx4x2-lnx2=12 lnx8-lnx2=12 lnx6=12

Parth (parthkohli):

Great!

Parth (parthkohli):

\[6\ln(x) = 12\]\[\ln(x) = 2\]

OpenStudy (rabya!):

Oh Ok Thanks !

OpenStudy (rabya!):

x4lnx-lnx=0 lnx(x4-1)=0 e(x4-1)=e0 wat aftr it ?

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