Question

3. The sum of first n terms of an arithmetic sequence
is n2 + 2n.
(a) What is the first term?
(b) Find the common difference.
(c) What is the sum of first 20 terms of this se-
quence?
(d) Prove that the sum of continuous terms starting
from the first of the sequence 3, 5, 7, .... added
to 1 gives a perfect square.​

Answer 1

Answer:

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Step-by-step explanation:

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