Show-that-in-fibonacci-sequence-f-3n-f-n-3-f-n-1-3-f-n-1-3- Tinku Tara July 13, 2023 Set Theory 0 Comments FacebookTweetPin Question Number 194709 by MM42 last updated on 13/Jul/23 Showthatinfibonaccisequencef3n=fn3+fn+13−fn−13 Answered by TheHoneyCat last updated on 14/Jul/23 Letφ:=1+52andψ:=1−52Youmightknowthatfn=φn−ψn5fromthatwecancompute:X=fn3+fn+13−fn−13=15×15((φn−ψn)3+(φn+1−ψn+1)3−(φn−1−ψn−1)3)=15×15(φ3n−3φ2nψn+3φnψ2n−ψ3n+φ3n+3−3φ2n+2ψn+1+3φn+1ψ2n+2−ψ3n+3−φ3n−3+3φ2n−2ψn−1−3φn−1ψ2n−2+ψ3n−3)=15(f3n+f3n+3−f3n−3)+35×5(−φ2nψn+φnψ2n−φ2n+2ψn+1+φn+1ψ2n+2+φ2n−2ψn−1−φn−1ψ2n−2)=15(f3n+f3n+1+f3n+2−f3n−3)+3φn−1ψn−15×5(−φn+1ψ+φψn+1−φn+3ψ2+φ2ψn+3+φn−1−ψn−1)=15(f3n+f3n+f3n−1+f3n+1+f3n−f3n−3)+3φn−1ψn−15×5(−φn+1ψ+φψn+1−φn+3ψ2+φ2ψn+3+φn−1−ψn−1)Nowthisisthemomentwhereyouusethefactthatψ=−1φX=15(3f3n+f3n−1+f3n+f3n−1−f3n−3)+3(−1)n+155(φn−ψn−φn+1+ψn−1+φn−1−ψn−1)=15(4f3n+f3n−1+f3n−2+f3n−3−f3n−3)+3(−1)n+15(fn−1+fn−fn+1)=15(4f3n+f3n−1+f3n−2)+0=15(4f3n+f3n)=f3nThereyougo. Terms of Service Privacy Policy Contact: info@tinkutara.com FacebookTweetPin Post navigation Previous Previous post: Question-194695Next Next post: Question-194697 Leave a Reply Cancel replyYour email address will not be published. Required fields are marked *Comment * Name * Save my name, email, and website in this browser for the next time I comment.