Which expression represents a difference of squares?

A. 81 - 49y^2

B. 4x^2 - 16x

C. t^2 + 100

D. 25k - 64

A. 81 - 49y²

Step-by-step explanation:

The triangle that represent a difference of squares is A.

It is easily recognize by looking at the numbers, the number gives a perfect square and the variable y is also squared

That is 9² = 81 and 7² = 49 and

Also the sign in-between them must me a negative sign, when the expression consist of the above, then it gives a different of square.

81 - 49y²

9² - 7²y²

(9 - 7y) (9 + 7y)

Lets open back the parenthesis to check our answer

(9 - 7y) (9 + 7y)

9 (9+7y) - 7y (9+7y)

81 + 63y - 63y - 49y²

81 - 49y²