Find nth term and Sum of n terms of given series
4+11+22+37+56+......
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⇒ 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
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★★★hope this may help u!!!★★★
_____________________________________________________________
⇒ 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!!!★★★
brits1106:
Can u please explain it couldn't get it...I was trying to solve it
aree 2st term is 4 then 2nd term is 11 then u have to add 4 + 7 and this will get u 11
then u have to add 4 +7+11 u will get 22
then u have to add 4+7+11+15 for yours 4th term then u will get 37.....
understood or not????
tell me....plzz
Wht is then nth term
I haven't understood a thing
Could you explain in a simplified manner
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