Answer:
the explicit formula for the geometric sequence 2,6,18,54 is 
2,6,18,54
Step-by-step explanation:
In the sequence given: 2,6,18,54
The common ration is 3 because
a₁ = 2
a₂= 2*3 =6
a₃ = (2*3)*3 = 2*3^2 = 18
a₄= (2*3*3)*3 =2*3^3 = 54
Here we see for a₂ 3 has power 1, for a₃ 3 has power 2 and so on.
So, the formula will be

Here aₙ is the no of term.
a₁ is the first term of the sequence
and r is the common ratio among the sequence.
Let the number be x, the square of x is x^2, then
The product of the square of x and 5 is 5x^2.
Calculate the circumference of the circle, and multiply it by 23.
C = pi * d
C = 3.14 * 63 ft =197.82 ft
23 * C = 23 * 197.82 ft = 4549.86 ft
B is the answer to your question.