Question

If a₁ = 7 and an = an-1 - 1 then find the value of a5.

Answer 1

• a₅ = 3

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Given AP with recursive formula:

• a₁ = 7 and aₙ = aₙ₋₁ - 1

As per recursive formula the first term is a₁ = 7 and common difference is d = -1.

Use the nth term formula to find the 5th term:

• aₙ = a₁ + (n - 1)d
• a₅ = 7 + (5 - 1)*(-1) = 7 - 4 = 3