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.

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Hi, I'm Ai Ling Ong. I enjoy coaching students who have challenges with understanding and scoring in 'O' Level A-Maths and E-Maths. I develop Math strategies, sometimes ridiculous ideas to help students in understanding abstract concepts the fast and memorable way. I write this blog to share with you the stuff I teach in my class, the common mistakes my students made, the 'way' to think, analyze... If you have found this blog post useful, please share it with your friends. I will really appreciate it! :)

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