LEARN · EXPLAIN · REVISE

Arrange m distinct people in a line with A and B adjacent.

Read the idea, work independently, then explain what changed.

TOPIC 01

Counting principles: mixed review

A mixed assessment: identify the method, justify it and revise your reasoning.

Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Transfer#Your turn

m=5

Counts use nonnegative integer sizes; decide whether labels, order and rotations distinguish outcomes.

Skills and prerequisite lessons

Working and explanation

BUILD THE REASONING

Hint 1

Decide whether choices are alternative cases or successive stages, then check overlap.

Hint 2

Treat A,B as one block.

Worked solution

Decide whether choices are alternative cases or successive stages, then check overlap.
Apply the stated relation and retain its conditions.
$N=2(m-1)!=48$
Multiply by two for AB and BA inside the block.

The requested value is 48.

Checks and common pitfalls: Multiply by two for AB and BA inside the block.

Think first. Reveal a hint when the class is ready.

Teacher preparation and assessment