Roots of (x+1)^n - x^2n = 0
cino hilliard
hillcino368 at hotmail.com
Fri May 28 01:34:14 CEST 2004
Hi,
While driving home from MicroCenter, I pondered on the golden ratio or the
solution to the
proportion: the lesser is to the greater as the greater is to the whole.
Then me thought what
if I say the square of the lesser is to the square of the greater as the
square or the greater is to
the square of the whole? This was a little heavy while driving so I waited
until I got home.
There I jotted out a^2/x^2 = x^2/(a+x)^2 and lo and behold for a =1 we
get 1/x^2 = x^2/
(x+1)^2 or (x+1)^2 - x^4 = 0. Lo and behold we get the roots 1/2 -
sqrt(5)/2 and 1/2 + sqrt
(5)/2. Curious I tried cubes, fourth powers etc and still got the same two
roots. So I concluded this
was generally true:
(x+1)^n - x^2n = 0 has real roots
x1 = 1/2 - sqrt(5)/2
x2 = 1/2 + sqrt(5)/2
for all n.
Proof anyone?
Maple solve(((x+1)^n - x^(n+n) = 0,x);
1/2 - sqrt(5)/2 ,1/2 + sqrt(5)/2
gives the result. Can this be considered a proof?
There are other interesting curios for (x+a)^n - x^2n = 0 has real roots
when a = 2,3,4 etc but different powers give different roots.
Have fun,
Cino
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