Again a logarithmic inequality

AI Thread Summary
The discussion revolves around solving a logarithmic inequality involving expressions like log3(9 - 3x) and log3(1 - 3x - 2). Participants suggest simplifying the expressions and solving the associated equation to identify critical points and discontinuities. Test points are recommended for determining the solution set. Graphing the function is also advised to visualize the behavior of the inequality. Ultimately, one user successfully converted the expressions into logarithmic form to find the solution.
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Homework Statement


i got stuck at the question below:-

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Homework Equations




The Attempt at a Solution


I tried to solve it by simplifying it but i got stuck at:-

250t2zb.png


Please help.
 
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Hi Pranav-Arora! :smile:

Just simplify the bottom …

what is the difference between log3(9 - 3x) and log3(1 - 3x-2) ? :wink:
 
tiny-tim said:
Hi Pranav-Arora! :smile:

Just simplify the bottom …

what is the difference between log3(9 - 3x) and log3(1 - 3x-2) ? :wink:

Sorry! Didn't get you...
 
One method for solving an inequality is to solve the associated equation; in this case that's

\frac{x-1}{\log_3(9-3^x)-3}=1.

Then the critical numbers are the solution set and any points of discontinuity.

Use test points (in the domain of the left hand side of the inequality) which either to the laeft or right of all the test points or between any pair of test point.

By the way, what is log3(9(1-3x-2)) ?
 
SammyS said:
One method for solving an inequality is to solve the associated equation; in this case that's

\frac{x-1}{\log_3(9-3^x)-3}=1.

Then the critical numbers are the solution set and any points of discontinuity.

Use test points (in the domain of the left hand side of the inequality) which either to the laeft or right of all the test points or between any pair of test point.

By the way, what is log3(9(1-3x-2)) ?

i think i forgot to mention, i need to find out the values of x.
 
Pranav-Arora said:
Sorry! Didn't get you...

Hi Pranav-Arora! :smile:

what is log3(9 - 3x) - log3(1 - 3x-2) ? :wink:
 
tiny-tim said:
Hi Pranav-Arora! :smile:

what is log3(9 - 3x) - log3(1 - 3x-2) ? :wink:

It would be

9 - 3x
-------
1 - 3x-2

But why i need to find this?
 
What is

9 - 3x
-------
1 - 3x-2

? :wink:
 
Try graphing \frac{x-1}{\log_3(9-3^x)-3} or \frac{x-1}{\log_3(9-3^x)-3}-1\,.

Remember that \log_3(a)=\frac{\ln(a)}{\ln(3)}
 
  • #10
SammyS said:
Try graphing \frac{x-1}{\log_3(9-3^x)-3} or \frac{x-1}{\log_3(9-3^x)-3}-1\,.

Remember that \log_3(a)=\frac{\ln(a)}{\ln(3)}

Whoops! i forgot it:-
\log_3(a)=\frac{\ln(a)}{\ln(3)}

I converted everything in log and then i was able to figure it out.

Thanks SammyS...:)
 
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