Question

The aun of the first 'n' terms of an A.P is 3n×2+5n find the A.P hence find its 16th term

Answer 1

HELLO DEAR,


The sum of n terms of an A.P. = 3n2+5n


then sum of (n-1) terms= 3(n-1)²+5(n-1)



So nth term of A.P will be Tn=3n2+5n-


3(n-1)²-5(n-1)= 3n²+5n-3n²-3+6n-5n+5=6n+2


in this way by putinng values of


n= 1,2,3,4,5,6,7,_______n-1, n


we will get the AP as

8,14,20,26,32,38,44,____and

the 16th term will be= 6*16+2=98


I HOPE ITS HELP YOU DEAR,
THANKS