Page 13: The Fermat Surface a^k + b^k = c^k + d^k
"Taxicab Numbers and the Fermat Surface a^k+b^k = c^k+d^k for k = 4,6,8"

The equation a^k+b^k = c^k+d^k for k =3 has a famous anecdote connected to it, namely the incident involving Ramanujan, Hardy, and the taxicab number 1729 (as if you didn't know already).
An example of a turn-of-the-century taxicab which might have been similar to the one ridden by Hardy. Note the number "5795".  For more images, visit the London Vintage Taxi Association.
In a previous paper we extended Euler's method of finding the complete rational parametrization of k = 3 to find a radical version for k = 5.  For this one, the generalization will be completed so that it can be applied for any k.  We will then:
    a) give a solution to the above equation for
k = 4 using fifth powers.
    b) find a radical four-parameter solution to
k = 6 which for certain parameters will be multi-grade for k = 2,4,6.
    c) a radical solution to
k = 8 that may involve, surprisingly, the Golden Ratio and the Plastic Constant.
Choose your format: (preferably the pdf)
Fermatsurface.pdf
Fermatsurface.htm
Page 12 Page 14
Index
This webpage was born Nov 29, 2005