The expression shown in the image is:

$49 - 81x^2$

This is a difference of squares. The general form of the difference of squares is:

$a^2 - b^2 = (a - b)(a + b)$

Let's identify $a$ and $b$ in the expression:

• $49$ is $7^2$, so $a = 7$.
• $81x^2$ is $(9x)^2$, so $b = 9x$.

Applying the difference of squares formula:

$49 - 81x^2 = (7 - 9x)(7 + 9x)$

Therefore, the factored form of $49 - 81x^2$ is:

$(7 - 9x)(7 + 9x)$

Would you like more details or have any questions?

Here are 5 related questions to expand your understanding:

1. How do you identify if an expression is a difference of squares?
2. Can the difference of squares be applied if one of the terms is not a perfect square?
3. What is the factored form of $16x^2 - 25$?
4. How would you factor $100 - x^4$?
5. How can you verify if your factored expression is correct?

Tip: Always check if each term in the expression is a perfect square before applying the difference of squares rule.