Class 10 Optional Mathematics | General Term (nth Term) of a Geometric Sequence

Optional Mathematics · Class 10 · Sequence and Series

General Term of a Geometric Sequence

Common ratio r · nth term formula · Worked examples

By the end of this lesson you can

🔍

Test whether a sequence is geometric

➗

Find the common ratio r

🧮

Use tn = ar^(n-1) to find any term

🎯

Find a, r or n from given terms

➖Differences

4 - 2 = 2

8 - 4 = 4

16 - 8 = 8

Not constant

➗Ratios

4 ÷ 2 = 2

8 ÷ 4 = 2

16 ÷ 8 = 2

Always 2

The notes are free to read in full.

Presenter notes: Today we meet sequences that grow or shrink by multiplying, and we find one formula that reaches any of their terms.