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Revision Notes

Logarithms

ICSE · Class 9 · Mathematics

Quick revision notes for Logarithms — ICSE Class 9 Mathematics. Key concepts, formulas, and definitions for last-minute revision.

34 questions25 flashcards5 concepts

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An infographic summarizing the three main laws of logarithms: product rule, quotient rule, and power rule, with examples.
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Key Topics to Revise

1

1. Meaning of Logarithm

  • A logarithm is another way to write an exponential statement.
  • If a^b = c, then log_a c = b.
  • The base must not be 1.
2

2. Basic Values of Logarithms

  • For any positive base x, x^0 = 1 gives log_x 1 = 0.
  • For any positive base x, x^1 = x gives log_x x = 1.
  • log_10 1000 = 3 because 1000 = 10^3.
3

3. Laws of Logarithms

  • Product Law: logarithm of a product equals the sum of logarithms.
  • Quotient Law: logarithm of a fraction equals the difference of logarithms.
  • Power Law: logarithm of a power equals the exponent times the logarithm.
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4. Common Logarithms and Change of Base

  • Logarithms to base 10 are called common logarithms.
  • If no base is written, the base is 10.
  • The reciprocal relation connects logs of two positive numbers at each other’s base.

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Full Notes

Key Concepts

If a^b = cThe statement a^b = cFor any positive xlog_a(m × n) = log_a mlog_a(m/n) = log_a m

Frequently Asked Questions

What are the important topics in Logarithms for ICSE Class 9 Mathematics?
Logarithms covers several key topics that are frequently asked in ICSE Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Logarithms — ICSE Class 9 Mathematics?
Understand the core concepts first, then work through the 34 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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