Question

Show that a1, ,a2 , ……,an ….. form an A.P where an = 3 + 2n. Also, find the sum of 1st 20terms.
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Answer 1

Answer:

an = a + (n-1)d

Step-by-step explanation:

3 + 2n =a1 + (an-1)(a2-a1).......[ d = t2-t1 = a2-t1 ]

3 + 2n = a1 + ana2 -ana1 -a2 + a1

3 + 2n = 2a1 + an(a2-a1)