Question

For the sequence 11,13,15,_,_,_, find the formula for the nth term​

Answer 1

aₙ = 9 + 2n

Explanation:

Formula for the nth term of an arithmetic sequence, aₙ with a common difference of d and first term of a₁ is

aₙ = a₁ + d(n-1)

The common difference is the difference between two consecutive terms and is a constant

Here d = 13- 11 = 15-13 = 2

First term is 11

nth term:

aₙ = 11 + 2(n-1)

aₙ = 11 + 2n -2

aₙ = 9 + 2n

So if you wanted the 10 term say it would be

a₁₀ = 9 + 2x 10 = 9 + 20 = 29

Answer 2

Answer: … 17,19,21,23,25,27

Since the patter is increasing by 2. Keep adding by 2 until you reach the ninth terms.

15+2= 17
17+2 = 19
19+2=21
21+2=23
23+2=25
25+2=27