Given , find the value of .
Working with logarithm is tricky, we try to transform the question to an exponential question.
Then, we have
Here comes the critical observation:
Observe that .
Divide throughout by , we get .
Solving using quadratic formula (and reject the negative value since and has to be positive for their logarithm to exist),
We get .
If you have any questions, please feel free to ask me by posting a comment, or emailing me.
(I will usually explain in much more detail if I teach in person, than when I type the solution)
7 thoughts on “O Level Logarithm Question (Challenging)”
Well done !
Good observation a(a+b) = b^2 which is the key leads to solving quadratic equation in (a/b).
I have liked the identity a(a+b)=b2. explain more
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Note that both and are equal to !
Reblogged this on Project ENGAGE.