CBSE MATHEMATICS • SELECTED CENTRAL & STATE COMPETITIVE EXAMS
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GANITA MANJARI · GRADE 9 · PART II · CHAPTER 9

REVERSE — Understanding the Converse

Think first. Use AI purposefully. Verify always.

01 · DISCOVER

Start by thinking.

Every multiple of 14 is even. Does being even force a number to be a multiple of 14?

02 · UNDERSTAND

Understanding the Converse

An if–then proposition has a starting condition and a conclusion. To form its converse, exchange those two parts and keep their meanings and domain unchanged. “P implies Q” has the same direction as “If P, then Q”.

03 · KEY IDEAS

Keep the conditions clear.

  • Original: If P, then Q. Converse: If Q, then P.
  • Reversing the arrow does not prove the reversed statement.
  • “Q when P” still starts from P; it is not the converse.

04 · VISUALISE

Follow the direction.

  1. Multiple of 14
  2. →
  3. Even

Every multiple of 14 has a factor 2. The arrow starts at multiple of 14.

05 · METHOD / REASONING

Make the argument checkable.

Name the starting condition P and the conclusion Q. Exchange them. Test the new direction independently.

06 · ORIGINAL AIMS WORKED EXAMPLE

Follow each step.

For positive integers: if n is a multiple of 14, then n is even.

  1. Write n = 14k = 2(7k), so the original is true.
  2. Converse: if n is even, then n is a multiple of 14.
  3. The value 2 is even but is not a multiple of 14. The converse is false.

07 · AIMS METHOD

Your turn to reason.

  1. Attempt independently
  2. Investigate the idea
  3. Make connections
  4. Scrutinise your reasoning

Reverse “If a shape is a square, then it is a rectangle”.

Compare after your own attempt

If a shape is a rectangle, then it is a square. A 3-by-7 rectangle disproves this converse.

08 · PRACTICE SPRINT

Use the idea in a new situation.

Ten original AIMS questions: 3 Warm-up, 4 Build, 2 Think and 1 Challenge.

Start Practice Sprint →

Check & Feedback: incorrect answers receive a conceptual hint and another attempt; correct answers include reasoning.

TEXTBOOK CONNECTION

Return to the source. Bring your reasoning.

Ganita Manjari · Grade 9 · Part II · Chapter 9. Use your textbook for the complete questions. These are topic references and original AIMS guidance, not reproduced exercises.

Textbook Guided Example

Example 1

Source page 1 · REVERSE

Everyday cause and a possible alternative cause

Identify the stated direction before reversing it. A different cause can defeat the converse.

AIMS reasoning checkpoint

Original AIMS parallel: a club member gets a card, but a visitor may receive the same card.

Textbook Guided Example

Example 2

Source page 2 · REVERSE

Divisibility in two directions

Write a general multiple as a product, then look for a multiple of the smaller divisor that fails the reverse.

AIMS reasoning checkpoint

Keep the original textbook numbers in your book; AIMS uses fresh numerical examples in REVERSE.

Exercise Practice

Exercise Set 9.1 · Q16

Source page 6 · REVERSE

Digit-sum test for divisibility by 3

Express each direction with an if–then sentence.

AIMS reasoning checkpoint

Keep the same positive integer in both sentences; the starting condition and conclusion exchange places.

All textbook references →