perplexus.info :: Numbers : Curious Cubic Calculation?

Home > Numbers

Curious Cubic Calculation? (Posted on 2004-10-13)

Show that α=ł√(7+5√2)+ł√(7-5√2) is an integer. No calculators or computers allowed!

See The Solution Submitted by Old Original Oskar!

Rating: 3.8333 (6 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)

inegrity by squaring

| Comment 1 of 14

square both sides
simplify

I BELIEVE a IS NOT an integer

HOWEVER IF YOU TAKE DIFFERENCE INSTEAD OF A SUM:
a^2=16
a=4
or a=-4:
QED

please confirm

please see my later post
Edited on October 15, 2004, 6:12 am

Posted by Ady TZIDON on 2004-10-13 12:49:02

Please log in:

Login:
Password:
Remember me:

Sign up! \| Forgot password

Search:

Search body:

Forums (1)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (6)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:


perplexus dot info