Question

Find nth term and Sum of n terms of given series
4+11+22+37+56+......

Answer 1

★★★heyaa friend!!!★★★
_____________________________________________________________

⇒ we see that
a1=4
a2=4+7
a3=4+7+11
a4=4+7+11+15
a5=4+7+11+15+19

so a_n=a_(n-1)+4n-1=a_(n-2)+4*(n-1)-1+4*n-1=....=a1+4*2-1+4*3-1+....+4*n-1=
=a1+4*( 2+3+4+...+n) -(n-1)=a1+4*(2+n)*(n-1)/2-(n-1)=a1+2*(n+2)*(n-1)-(n-1)= =a1+(n-1)(
2(n+2)-1)=a1+(n-1)*(2n+3)=4+(n-1)(2n+3)
Hence a_n=4+2n^2+n-3=2n^2+n+1

___________________________________________________________

if u like mine answer plzz mark me at brainlist........

★★★hope this may help u!!!★★★

Answer 2

Answer:

Step-by-step explanation: