Question:
Which summation formula represents the series below? 1 + 2 + 6 + 24
(a)
(b)
(c)
(d)
Answer:
Option a: is the correct answer.
Explanation:
Option a:
By substituting the values of n and expanding the summation, we have,
Subtracting, we have,
Expanding the factorial,
Simplifying, we get,
Thus, the summation represents the series
Hence, Option a is the correct answer.
Option b:
By substituting the values of n and expanding the summation, we have,
Expanding the factorial,
Simplifying, we get,
Thus, the summation does not represents the series
Hence, Option b is not the correct answer.
Option c:
By substituting the values of n and expanding the summation, we have,
Adding, we have,
Expanding the factorial,
Simplifying, we get,
Thus, the summation does not represents the series
Hence, Option c is not the correct answer.
Option d:
By substituting the values of n and expanding the summation, we have,
Expanding the factorial,
Simplifying, we get,
Thus, the summation does not represents the series
Hence, Option d is not the correct answer.
Hence, the correct answer is Option a: