Final answer:
The expression that represents the area of the trapezoid is b) (6k² + 78k + 240).
Step-by-step explanation:
The area of a trapezoid is found using the formula A = 1/2h(b₁ + b₂), where h is the height and b₁ and b₂ are the bases. To determine which expression represents the area of the trapezoid, we can compare the given expressions with the formula. Let's calculate the area with each expression and see which one matches.
Expression a: (6k² + 240)
Expression b: (6k² + 78k + 240)
Expression c: (6k + 39)
Expression d: (3k² + 120)
Comparing the given expressions with the formula, we can see that expression b: (6k² + 78k + 240) matches the formula A = 1/2h(b₁ + b₂). Therefore, the correct expression that represents the area of the trapezoid is option b.