Question

 

 

Find the 7^th term of the sequence whose n^th term is given by the formula t_n = n(n + 2).

	A.	3
	B.	8
	C.	35
	D.	63

 

What is the common ratio of the following geometric sequence? 5, 15, 45...

	A.	3
	B.	5
	C.	15
	D.	1/3

 

Answer 1

(1).

The nth term of the sequence : t_n = n(n + 2).

To find 7th term, substitute n = 7 in the above nth term.

t₇ = 7(7 + 2)

    = 7(9)

    = 63.

The option D is correct.

Answer 2

(2).

The geometric sequence : 5, 15, 45, t_n = n(n + 2) · · · · · ·.

Common ratio = The ratios of consecutive terms.

Common ratio : r = 15/5 = 45/15 = 3.

The option A is correct.