Q25 of 202 Page 9

Find the sum of first 20 terms of these sequence whose nth term is .

Given, an= An + B

Put n = 1, a1= A + B


Put n = 20, a20= 20A + B


S20= [a + l]


= 10 [A + B + 20A + B]


= 10 [21A + 2B]


= 210A + 20B


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