Question and Answers Forum

All Questions      Topic List

None Questions

Previous in All Question      Next in All Question      

Previous in None      Next in None      

Question Number 175264 by Beginner last updated on 25/Aug/22

Answered by Rasheed.Sindhi last updated on 25/Aug/22

S_n =5n^2 −2n=n(5n−2) U_r =S_r −S_(r−1) =(5r^2 −2r)−( 5(r−1)^2 −2(r−1) ) =5r^2 −2r−5(r^2 −2r+1)+2(r−1) =5r^2 −2r−5r^2 +10r−5+2r−2 =10r−7 d=U_r −U_(r−1) (say) =(10r−7)−( 10(r−1)−7 ) =10r−7−10(r−1)+7 =10r−7−10r+10+7 =10 As d (difference between consecutive terms) is constant, U_r is an AP

Sn=5n2−2n=n(5n−2)Ur=Sr−Sr−1=(5r2−2r)−(5(r−1)2−2(r−1))=5r2−2r−5(r2−2r+1)+2(r−1)=5r2−2r−5r2+10r−5+2r−2=10r−7d=Ur−Ur−1(say)=(10r−7)−(10(r−1)−7)=10r−7−10(r−1)+7=10r−7−10r+10+7=10Asd(differencebetweenconsecutiveterms)isconstant,UrisanAP

Terms of Service

Privacy Policy

Contact: info@tinkutara.com