Question

find the sum of first 20 terms of the AP 3,8,13....using formula
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Answer 1

Answer:

a= 3

d= 5

n= 20

Sn= n/2{2a+ (n-1)d}

20/2{2(3)+(20-1)(5)}

10{ 6+ (19)5}

10{ 6 +95}

10{101}

1010