A square model has area s² − 14s + 49. What is the side length of the small corner square?

Correct answer: 7

The correct answer is D, 7 units. Rewrite the expression as a perfect square: s² − 14s + 49 = s² − 2(s)(7) + 7² = (s − 7)². In the visual model, the constant term 49 represents the area of the small corner square. A square with area 49 has side length √49 = 7, taking the positive root because a length is positive. Option A, 14, is the coefficient of the middle term, not the side length. Option B, 49, is the small square’s area, not its side. Option C, 2, is the numerical factor in the identity and does not represent the cut-out side. Option D is correct because 7² gives the constant term 49 and 2 × s × 7 gives the middle term 14s. Memory cue: in (s − a)², the corner square has area a² and side a.