Question

find the sum of first 5 terms of A. P. whose Nth term is 2n-3​

Answer 1

Answer:

an=2n-3

a1=2*1-3=-1

simlarly,

a2=1

a3=3

Now,

sn=n/2(2a+(n-1)d)

putting values

sn=15

Answer 2

Answer :

step by step explanation

1st term = a= 2(1)-3 = -1

5th term (i e.last term) = 2(5)-3= 7

sum of five terms = S = n/2 ( a+ last term)

=5/2 (-1+7)

= 15