Answer
$$3(x - 5)(x + 5)$$
Work Step by Step
Looking at this expression, we can see that a $3$ can be factored out from each term:
$$3(x^2 - 25)$$
After the $3$ was factored out, we have the difference of two squares left. We can factor this binomial according to the following formula:
$$A^2 - B^2 = (A - B)(A + B)$$
where $A$ is the square root of the first term and $B$ is the square root of the second term.
In this problem, $A$ is the $\sqrt x^2$ or $x$ and $B$ is the $\sqrt 25$ or $5$. We can plug these values into the formula:
$$3(x - 5)(x + 5)$$
