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SS1: MATHEMATICS - 1ST TERM

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  1. Number Base System I | Week 1
    6 Topics
    |
    2 Quizzes
  2. Number Base System II | Week 2
    3 Topics
  3. Number Base System III | Week 3
    2 Topics
    |
    1 Quiz
  4. Modular Arithmetic I | Week 4
    2 Topics
  5. Modular Arithmetic II | Week 5
    3 Topics
  6. Modular Arithmetic III | Week 6
    4 Topics
    |
    1 Quiz
  7. Indices I | Week 7
    3 Topics
    |
    1 Quiz
  8. Indices II | Week 8
    1 Topic
    |
    1 Quiz
  9. Logarithms I | Week 9
    3 Topics
  10. Logarithms II | Week 10
    4 Topics
    |
    1 Quiz



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Topic Content:

  • Laws of Logarithms
  • Changing the Base of a Logarithm

1) \( \scriptsize \log_a MN = \log_a M \: +\: \log_aN \\ \rightarrow \scriptsize a^x \: \times \: a^y \\ \scriptsize = a^{x + y} \)

2) \( \scriptsize \log_a \normalsize\left (\frac{M}{N} \right ) \scriptsize = \log_a M \: – \: \log_aN \\ \rightarrow \scriptsize a^x \div a^y \\ \scriptsize = a^{x – y}\)

3) \(\scriptsize \log_{a} \left ( M^{n} \right ) = n \log_{a} M \\ \scriptsize \rightarrow \left ( a^{x} \right )^{y} = a^{xy} \)

(for any base “a” > 0, where \( \scriptsize a \neq 1\))


  • Note that the three basic laws of logarithms are closely related to those of indices given earlier on.
  • Note that \( \frac {\log M}{\log N} \scriptsize \neq \log M \; – \log N \)⚠️ (Very Important)

Special Logarithms

4) \(\scriptsize \log_{a}a = 1 \\ \scriptsize\rightarrow a^1 = a \)

 

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Example: Evaluating \( {\color{Yellow}\scriptsize \log_2(50) }\)

If your goal is to find the value of a logarithm, change the base to 10 or e since these logarithms can be calculated on most calculators.

So let’s change the base of  \( \scriptsize \log_2 50 \; to \; 10 \)

Change of base rule \( \scriptsize \log_{b} (a) = \normalsize \frac{\log_x (a)}{\log_x (b)} \)

Using this rule, a = 50, b = 2, x = 10

\( \therefore \scriptsize \log_{2} (50) = \normalsize \frac{\log_{10} (50)}{\log_{10} (2)} \)

= \( \frac{\log (50)}{\log(2)} \)

Using a calculator this gives 5.644

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