Answer:
see explanation
Step-by-step explanation:
Given d = - 3 and a₄ = 17
To obtain terms before a₄ , then do the opposite and add 3 , that is
a₃ = a₄ + 3 = 17 + 3 = 20
a₂ = a₃ + 3 = 20 + 3 = 23
a₁ = a₂ + 3 = 23 + 3 = 26
Then arithmetic sequence is
26, 23, 20, 17, ...........
