wu :: forums « wu :: forums - n^4 + 4 » Welcome, Guest. Please Login or Register. Apr 29th, 2024, 7:37am

RIDDLES SITE WRITE MATH! Home Help Search Members Login Register

wu :: forums    riddles    easy (Moderators: SMQ, Icarus, william wu, ThudnBlunder, Grimbal, Eigenray, towr)    n^4 + 4 « Previous topic | Next topic » Pages: 1  Reply Notify of replies Send Topic Print    Author  Topic: n^4 + 4  (Read 603 times) NickH Senior Riddler     Gender: Posts: 341 n^4 + 4   « on: Jan 25th, 2003, 4:18pm » Quote Modify An easy one...   Show that, for integers n > 1, n4 + 4 is never prime. IP Logged Nick's Mathematical Puzzles BNC Uberpuzzler     Gender: Posts: 1732 Re: n^4 + 4   « Reply #1 on: Jan 26th, 2003, 1:03am » Quote Modify n^4+4= (n^2)^2+2^2= (n^2+2)^2-2*2*n^2= (n^2+2)^2-4n^2= [(n^2+2)+2n]*[(n^2+2)-2n]= (n^2+2n+2)*(n^2-2n+2)   n^2+2n+2 > 1 for n>1 n^2-2n+2 > 1 for n>1   QED IP Logged How about supercalifragilisticexpialidociouspuzzler [Towr, 2007] Pages: 1  Reply Notify of replies Send Topic Print Forum Jump: ----------------------------- riddles -----------------------------=> easy   - medium   - hard   - what am i   - what happened   - microsoft   - cs   - putnam exam (pure math)   - suggestions, help, and FAQ   - general problem-solving / chatting / whatever ----------------------------- general -----------------------------  - guestbook   - truth   - complex analysis   - wanted   - psychology   - chinese « Previous topic | Next topic »

Powered by YaBB 1 Gold - SP 1.4!
Forum software copyright © 2000-2004 Yet another Bulletin Board