Question

The sum of first n terms of an ap is goven by sn = 2n2+3n find the 16 th term if an ap

Answer 1

Sum of 1 term=2*1*1+3*1=5

Therefore a=5

Sum of 1st 2 terms = 2*(2)2+3*2=14

Now 1st term is 5 second term will be

14-5=9

D=9-5=4

Sum of 1st 16 terms will be 16/2[2*5+(16-1)4]

8[10+60]=8*70 =560 ans.