LEARN · EXPLAIN · REVISE

Find a3a7 given a5=t.

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

TOPIC 01

Sequences: 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 / Standard#Your turn

t=30

Skills and prerequisite lessons

Working and explanation

BUILD THE REASONING

Hint 1

Use the common ratio and check its special cases.

Hint 2

Use this intermediate relation.

a_3a_7=a_5^2

Worked solution

Use the common ratio and check its special cases.
Apply the stated relation and retain its conditions.
$a_3a_7=a_1^2q^8=a_5^2=900$
Equal index sums give equal products in a nonzero geometric sequence.

The requested value is 900.

Checks and common pitfalls: Equal index sums give equal products in a nonzero geometric sequence.

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

Teacher preparation and assessment