To know which option is correct, we shall use the formula suggested by both Khaled and Wilma to see which will give the sequence given in the question.
For Khaled:
F(n) = 1 • 3ⁿ¯¹
n = 1
F(n) = 1 • 3ⁿ¯¹
F(1) = 1 • 3¹¯¹
F(1) = 1 • 3⁰
F(1) = 1 × 1
F(1) = 1
n = 2
F(n) = 1 • 3ⁿ¯¹
F(2) = 1 • 3²¯¹
F(2) = 1 • 3¹
F(2) = 1 × 3
F(2) = 3
n = 3
F(n) = 1 • 3ⁿ¯¹
F(3) = 1 • 3³¯¹
F(3) = 1 • 3²
F(3) = 1 × 9
F(3) = 9
For Wilma
F(n) = 1 • 3ⁿ
n = 1
F(n) = 1 • 3ⁿ
F(n) = 1 • 3¹
F(1) = 1 × 3
F(1) = 3
n = 2
F(n) = 1 • 3ⁿ
F(2) = 1 • 3²
F(2) = 1 × 9
F(2) = 9
n = 3
F(n) = 1 • 3ⁿ
F(3) = 1 • 3³
F(3) = 1 × 27
F(3) = 27
SUMMARY
Using Khaled's formula i.e F(n) = 1 • 3ⁿ¯¹ we obtained 1, 3, 9,..
Using Wilma's formula i.e F(n) = 1 • 3ⁿ
We obtained 3, 9, 27,..
Now, comparing the sequence obtained using the formula of both Khaled and Wilma, we can see that only the sequence of Khaled is the same with the one given in the question. Therefore, only Khaled's formula is correct.
