Question

Find the sum of first 18 terms of AP whose first term is 5 and Common difference is 2

Answer 1

a= 5

d= 2

n=18

by formula...

Sn = n/2 [2a+(n-1)d]

Sn = 18/2[ 2× 5+(18-1)2]

Sn = 9[10+17 × 2]

Sn = 9[ 10+ 34]

Sn = [ 9× 44]

Sn =. 396 Answer...

Hence the sum is 396........