Which of the following must be true for an expression to be a difference of two squares?

In order for an expression to qualify as a difference of two squares, it must be in the form of a² – b². This means that there are two square terms being subtracted from each other.

This expression can also be factored into the product of two binomials as follows: (a – b)(a + b). For both of these conditions to hold, the two components (a and b) must be real numbers and squares, which means they can be expressed as the square of another real number.

Here are a few key points that clarify this concept:

• Square Terms: Both a and b need to be perfect squares. For instance, 1, 4, 9, etc., are perfect squares.
• Subtraction: The operation must be a subtraction between the two squares, not addition or any other operation.

So, to summarize, for an expression to be a difference of two squares, it has to consist of two square terms being subtracted, which can be expressed in the form a² – b².