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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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Index form: base and index
40 min · 1 practice tasks · quizA number in index form is a base with an index. The index counts equal factors of the base.
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Multiply powers: add the indices
40 min · 1 practice tasks · quizWhen the bases are the same, multiply powers by adding the indices. Generate the law by expanding factors.
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Divide powers: subtract the indices
40 min · 1 practice tasks · quizWhen the bases are the same, divide powers by subtracting the indices. Cancel equal factors.
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Power of a power: multiply the indices
40 min · 1 practice tasks · quizA power raised to a power multiplies the indices. Expand as a repeated product of the inner power.
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Zero index and index one
40 min · 1 practice tasks · quizAny non-zero number to the power 0 is 1. A number to the power 1 is itself. Generate a^0 from the division law.
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Powers of 10 and common logarithms
40 min · 1 practice tasks · quizA 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.