Question

plz solve this question ,question. no. 8

Answer 1

S= 2n + 3n^2

put n= 1, u will get first term

S1 = 2 + 3 = 5

For Second term

S( n= 2) - S( n= 1)

2(2) +3( 2^2) - 5

4 + 12 -5

11

So AP is 5,11, 17....


rth term = 5 + ( r-1) 6

Answer 2

Answer:

Step-by-step explanation:

given-- sn=(2n+3n^2)

when n=1, s1= 2*1+3*1^2=2+3=5 therefore a=5

n=2, s2= 2*2+3*2^2 = 4+ 12 =16 therefore a2=16-5=11

hence d= 11-5 =6

therefore AP is 5,11,17,23......

and rth term is

ar = a+(r-1)d

   =5+(r-1)6

   =5+6r-6

ar= 6r-1