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1.3 Indices and Logarithms

Mathematics · Grade 9 · 6 lessons in the design

What this covers

  • Numbers in index form
  • Laws of indices
  • Powers of 10 to common logarithms

What you will be able to do

  • express numbers in index form in different situations
  • generate the laws of indices in different situations
  • apply the laws of indices in different situations
  • relate powers of 10 to common logarithms in different situations
  • appreciate the use of indices and logarithms in real-life situations

Key questions

“How do we express numbers in powers?”

Lessons

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  1. Index form: base and index
    40 min · 1 practice tasks · quiz
    A number in index form is a base with an index. The index counts equal factors of the base.
  2. Multiply powers: add the indices
    40 min · 1 practice tasks · quiz
    When the bases are the same, multiply powers by adding the indices. Generate the law by expanding factors.
  3. Divide powers: subtract the indices
    40 min · 1 practice tasks · quiz
    When the bases are the same, divide powers by subtracting the indices. Cancel equal factors.
  4. Power of a power: multiply the indices
    40 min · 1 practice tasks · quiz
    A power raised to a power multiplies the indices. Expand as a repeated product of the inner power.
  5. Zero index and index one
    40 min · 1 practice tasks · quiz
    Any non-zero number to the power 0 is 1. A number to the power 1 is itself. Generate a^0 from the division law.
  6. Powers of 10 and common logarithms
    40 min · 1 practice tasks · quiz
    A common logarithm is the index when a number is written as a power of 10. Read it from the power, from tables, or from a calculator.