Question

The fifth term of an arithmetic sequence is 23 and the 12th term is 72
Determine the first three terms of the sequence ​

Answer 1

Answer:

Step-by-step explanation:

a₁₂ = a₅ + (12-5)d

72 = 23 + 7d

d = 7

a₃ = a₅ + (3-5)d = 23 - 2⋅7 = 9

a₂ = a₃ - d = 9-7 = 2

a₁ = a₂ - d = 2 -7 = -5