1) The
original swimming pool has a length of 18 feet, and 2) the new swimming pool will be 3x feet longer
=> new length = 18 + 3x
3) the original swimming poll has a width of 12 feet, the new swimming pool will be x feet wider
=> new width = 12 + x
New area = new length * new width
=> new area = (18 + 3x)(12 + x)
Apply distributive property: 18 * 12 + 18x + 12*3x + 3x*x
=> 216 + 54x + 3x^2
4) arrange in decrasing order:
=> 3x^2 + 54x + 216
Answer: option B. f(x) = 3x^2 + 54x + 216
