If Sn= 5n2+ 2n, find Tr? – InterviewSolution

1.	If Sn= 5n2+ 2n, find Tr?
Answer» S1=5(1)^2+2(1)=5+2=7and S2=5(2)^2+2(2)=5(4)+4=20+4=24henceSn=n/2(2a+(n-1)dwhen n=17=1/2(2a)=ahence a=7henceS2=2/2(27+d)=2424=14+dd=10hence Tn=a+(n-1)dhenceT =7+(n-1)10

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