In the model of x² + 2xy + y², if x² and y² are at two corners, what are the remaining two parts?

Correct answer: xy and xy, two equal rectangles

The correct answer is two rectangles, each with area xy. The identity (x + y)² = x² + 2xy + y² can be represented by a large square divided into four parts: one square of area x², one square of area y², and two rectangles. Each rectangle has side lengths x and y, so each has area xy. Together, the two rectangles contribute xy + xy = 2xy, which explains the middle term. Option A lists side lengths rather than the areas of the remaining regions. Option B incorrectly says each rectangle has area 2xy; then their total would be 4xy. Option D repeats the two square regions and does not account for the middle term. A useful memory cue is that the middle term in a square identity is made from two equal cross-rectangles, not one large rectangle.