Question

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

Answer 1

Options a and b.

A difference of two squares means that both numbers in the equation have to be square numbers. There will never be a difference of two squares with more than two terms, hence the name "difference of TWO squares."
For example: one difference of two squares is:
x^2-16. You can evenly take the square root of both x^2 and 16, getting results of x and 4.