When solving geometric sequence problems in Year 9, I’ve found some simple steps really helpful. Here’s how I usually work through them:

1. Identify the Sequence: First, check if you have a geometric sequence. In these sequences, each term is found by multiplying the previous term by a special number called the common ratio (r).

2. Find the First Term: Look for the first term (a) of the sequence. It’s usually given, but sometimes you have to spot it from a list.

3. Calculate the Common Ratio: To find r, divide any term by the term before it: $r = \frac{a_n}{a_{n-1}}$

4. Use the Formula for the Sum: If you need to find the sum of the first n terms ($S_n$) of a geometric sequence, use this formula: $S_n = a \frac{1 - r^n}{1 - r} \quad \text{(if } r \neq 1\text{)}$

5. Plug in Your Values: Once you have your a, r, and n, just put them into your formula.

6. Calculate: Remember to do the math carefully!

From what I’ve seen, practicing with different examples really helps you get better. Geometric sequences can be a lot of fun once you start to understand them!