What expression results from (a-b)(a-b)?

The expression ((a-b)(a-b)) is an application of the formula for the square of a binomial, which states that ((x-y)^2 = x^2 - 2xy + y^2). In this case, substituting (x) with (a) and (y) with (b), we apply the formula as follows:

1. The first part of the formula, (x^2), corresponds to (a^2).
2. The second part of the formula, (-2xy), corresponds to (-2ab).

3. The third part of the formula, (y^2), corresponds to (b^2).

Combining these parts gives us the complete expression:

[ (a-b)(a-b) = a^2 - 2ab + b^2 ]

Thus, the resulting expression from multiplying ((a-b)) by itself is (a^2 - 2ab + b^2). This aligns perfectly with the correct answer, confirming its validity.