Math, asked by Trash11, 1 year ago

In A.P 1st term = 1 last term = 20 . Their sum = 399 . Find n = ?

Answers

Answered by rahulmandviya

5

a = 20
tn = 20
sn = 399
Sn = n/2(a+l)
399 = n/2(1+20)
698 = 21n
n = 38

Trash11: ohk

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