Question

Find the first four terms of the sequence given by the formula:

Answer 1

Answer: Choice D. 2, 6, 12, 20

=============================================

Work Shown:

Plug in n = 1

c(n) = n(n+1)

c(1) = 1(1+1)

c(1) = 1(2)

c(1) = 2

The first term is 2

-------------

Plug in n = 2

c(n) = n(n+1)

c(2) = 2(2+1)

c(2) = 2(3)

c(2) = 6

The second term is 6

-------------

Plug in n = 3

c(n) = n(n+1)

c(3) = 3(3+1)

c(3) = 3(4)

c(3) = 12

The third term is 12

-------------

Plug in n = 4

c(n) = n(n+1)

c(4) = 4(4+1)

c(4) = 4(5)

c(4) = 20

The fourth term is 20

-------------

The first four terms are: 2, 6, 12, 20

Answer 2

Answer:

  d. 2,6,12,20

Step-by-step explanation:

You only need to compute c_n for n=1 to choose the correct answer:

  c1 = 1(1+1) = 2 . . . . . matches choice D