Final answer:
The area of the square with a side length expression of (x+4) is found by squaring the expression, which results in the polynomial x² + 8x + 16.
Step-by-step explanation:
The area of a square is calculated by squaring the length of one side. In this case, the side of the square is represented by the expression (x+4). To find the area, we multiply this expression by itself:
(x + 4) × (x + 4)
Using the distributive property (also known as the FOIL method for binomials), we get:
x × x = x²
x × 4 = 4x
4 × x = 4x
4 × 4 = 16
Combining like terms, we add 4x and 4x to get 8x, and the final polynomial representing the area of the square is:
x² + 8x + 16
Therefore, the correct answer is:
(a) x² + 8x + 16