## Factoring the Expression (9a² - 1/49b²) (3a - 1/7b)

This expression can be factored using the difference of squares pattern and then simplified. Let's break down the steps:

### 1. Recognizing the Difference of Squares

The first part of the expression, (9a² - 1/49b²), fits the pattern of the difference of squares:

**a² - b² = (a + b)(a - b)**

In this case:

- a = 3a
- b = 1/7b

### 2. Applying the Pattern

Applying the difference of squares pattern, we get:

(9a² - 1/49b²) = (3a + 1/7b)(3a - 1/7b)

### 3. Combining with the Remaining Factor

Now we can combine this result with the remaining factor, (3a - 1/7b):

### 4. Simplifying

Notice that we have (3a - 1/7b) as a factor twice. We can simplify this to:

**(3a + 1/7b)(3a - 1/7b)²**

### Final Factored Form

The fully factored expression is: **(3a + 1/7b)(3a - 1/7b)²**