Logarithm Equation Question 1

I met a student and she passed me this paper with this Lg question on it, asking me on the solution for solving this equation : $\lg(x-2)=(lg3)^2$

Coincidentally, I was asking a few O Level students of mine on which are the “Killer A-Maths Topics” for them. Logarithm, Indices, Surds is one of the common topic which is ranked high on their list.

Now back to the question.

PS: $lg = log_{10}$

Notice that right hand side of the equal sign is something you can compute using the calculator hence,

$\lg(x-2)=(lg3)^2$
$(x-2)= 10^{(lg3)^2}$

Use your calculator to find out the value of $10^{(lg3)^2}$ and the value is 1.69 ( round off to 3 significant figure) so the answer for this question is

$x = 1.69 + 2<br> =3.69<br>$

I will be coming out with a series of posts on Logarithms since it is a “hot” topic for students :-) Subscribe to my feeds to be updated of this post.

jiahui

February 25, 2008 | 7:26 pm

hey ailing.
thanks!

singaporeolevelmaths | Revisit: A-Math Logarithms Equations

November 15, 2008 | 3:59 pm

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