Question

If the nth term of a number sequence is n^2 + 2n,
find the first 3 terms and the 10th term.

Answer 1

3, 8, 15 and 120

Explanation:

to find the first 3 terms, substitute n = 1, 2, 3 into the nth term rule

n = 1 : 1² + 2(1) = 1 + 2 = 3

n = 2 : 2² + 2(2) = 4 + 4 = 8

n = 3 : 3² + 2(3) = 9 + 6 = 15

the first 3 terms are 3, 8, 15

to find the 10th term , substitute n = 10 into the rule

n = 10 : 10² + 2(10) = 100 + 20 = 120