Two strips of width 7 are added along two sides of an x by x square, and a 7 by 7 corner square is added. What is the new area?

Correct answer: x² + 14x + 49

The correct answer is B: x² + 14x + 49. Start with the original x by x square, whose area is x². The first added strip has dimensions x and 7, so its area is 7x. The second strip has the same dimensions and also has area 7x. Thus the two strips together contribute 14x. The corner is a 7 by 7 square, so its area is 49. Adding all four pieces gives x² + 7x + 7x + 49 = x² + 14x + 49. This is exactly (x + 7)². Option A includes only one strip and therefore misses 7x. Option C assigns 49 to the coefficient of x and 14 to the constant term, confusing the pieces. Option D uses negative middle terms, which would describe removing strips rather than adding them. A reliable check is to count the two identical x by 7 rectangles separately before combining them. The number of strips determines the coefficient 2 × 7 = 14.