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Simplify the following expression:
[tex]\[ -9a^2x^2 + 1 \][/tex]
[tex]\[ (a - b) \cdot (a + b) \][/tex]
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Answer :

Let's simplify the given expression step-by-step:

[tex]\[ \frac{-9a^2 x^2 + 1}{(a - b)(a + b)} \][/tex]

### Step 1: Simplifying the Numerator

First, look at the numerator:
[tex]\[ -9a^2 x^2 + 1 \][/tex]

Notice that this can be written as:
[tex]\[ -(9a^2 x^2 - 1) \][/tex]

We recognize that [tex]\( 9a^2 x^2 - 1 \)[/tex] is a difference of squares, because it is of the form [tex]\( a^2 - b^2 \)[/tex] where [tex]\( a = 3ax \)[/tex] and [tex]\( b = 1 \)[/tex]. Recall the difference of squares formula:

[tex]\[ a^2 - b^2 = (a - b)(a + b) \][/tex]

Applying this to [tex]\( 9a^2 x^2 - 1 \)[/tex]:
[tex]\[ 9a^2 x^2 - 1 = (3ax)^2 - 1^2 = (3ax - 1)(3ax + 1) \][/tex]

Therefore:
[tex]\[ -(9a^2 x^2 - 1) = -(3ax - 1)(3ax + 1) \][/tex]

So the numerator becomes:
[tex]\[ -[(3ax - 1)(3ax + 1)] \][/tex]

### Step 2: Analyzing the Denominator

The denominator is:
[tex]\[ (a - b)(a + b) \][/tex]

### Step 3: Combining Numerator and Denominator

Now, we can rewrite the original expression with the factored forms of both the numerator and the denominator:
[tex]\[ \frac{-[(3ax - 1)(3ax + 1)]}{(a - b)(a + b)} \][/tex]

### Step 4: Final Simplification

The expression:
[tex]\[ -[(3ax - 1)(3ax + 1)] \][/tex]

is simply a representation of the product, so the simplified form of the expression is:
[tex]\[ -\frac{(3ax - 1)(3ax + 1)}{(a - b)(a + b)} \][/tex]

This is the simplified form of the original given expression:

[tex]\[ -\frac{(3ax - 1)(3ax + 1)}{(a - b)(a + b)} \][/tex]