Arithmetic Sequence Help

Question

Find a formula for the general term a_n of the sequence assuming the pattern of the first few terms continues.

{11,13,15,17,19,...}

Assume the first term is a₁

a_n =   

Answer 1

an = a1 + d(n-1)

an = a1 + 2(n-1)

an = 11 + 2(n-1)

d=2 = the common difference = the difference between any term and the preceding term= 2

a1 = 1st term = 11

a1 = 11 + 2(1-1) = 11+0= 11

a2 = 11 + 2(2-1) = 11 +2 = 134

a3 = 11 + 2(3-1) = 11 +4 = 15

a4 = 11 + 2(4-1) = 11 + 6 = 17

a5 = 11 + 2(5-1) = 11 + 8 = 19

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