Question

2.) The sum of 1st 'n' terms of an
AP is given by (n2+8n). Find the 12th
term of AP. Also find the nth term of the AP
​

Answer 1

sum of first n terms = n²+8n

Sn = n/2[ a+an] = n² +8n

n/2[a+ an] = n(n+8)

a+an = 2×(n+8)

a+an = 2n+16

an = 2n+16 -a .......(1) is nth term

we have to find a12

n= 12

put in (1)

a12 = 2(12)+16-a

a12 = 24+16 -a

a12= 40 - a

i hope it will help u