Question

If the sum of nth term of an A.P is 2n^2+5n then find the 4th term

Answer 1

S4=2*4^2+5*4

=>S4=2*16+20

=>S4=32+20

=>S4=52

S3=2*3^2+5*3

=>S3=2*9+15

=>S3=18+15

=>S3=33

a4=S4 - S3

=>a4=52 - 33

=>a4=19