What are the first four terms of the sequence represented by the expression n(n – 1) – 5?
A. –7, –5, –3, 1
B. –5, –10, –15, –20
C. 0, 2, 6, 12
D. –5, –3, 1, 7
We can expand the expression to get:
n(n – 1) – 5 = n^2 – n – 5
To find the first four terms, we plug in n = 1, 2, 3, and 4:
- For n = 1, we get 1^2 – 1 – 5 = -5.
- For n = 2, we get 2^2 – 2 – 5 = -1.
- For n = 3, we get 3^2 – 3 – 5 = 1.
- For n = 4, we get 4^2 – 4 – 5 = 7.
Therefore, the first four terms are -5, -1, 1, 7, which is answer choice (D).