Answer:
The correct answer is C. A(x) = 480/x +2x²
Explanation:
1. Let's review the information given to us to answer the problem correctly:
Volume of a rectangular prism with square base = 120 cubic feet
Side of the square base = x
Height of the prism = h
2. Write the surface area of the prism as a function A(x) of the length of the side of the square x.
Let's find out A(x) this way:
Volume of a rectangular prism with square base = 120 cubic feet
x² * h = 120
h = 120/x²
Now, let's substitute h in the surface area formula, this way:
Surface area = 2 * side of the square base² + 4 * side of the square base * height
A(x) = 2x² + 4x * 120/x² (Recall 120/x² = h and side of the square = x)
A(x) = 2x² + 480x/x²
A(x) = 2x² + 480/x
The correct answer is C. A(x) = 480/x +2x²