HERONIAN INDETERMINATE EQUATIONS 445
number 3 is of course only an illustration, and the problem is
equivalent to the solution of the equations
(1) u + v = n(x + y) |
(2) xy — n.uv j
The solution given in the text is equivalent to
x = 2ft 3 - 1, y — 2 n 3 )
u = n{4:n z —2), v = n j
Zeuthen suggests that the solution may have been obtained
thus. As the problem is indeterminate, it would be natural
to start with some hypothesis, e.g. to put v — n. It would
follow from equation (1) that u is a multiple of n, say nz.
We have then
x + y = 1 + z,
while, by (2), xy = n 3 z,
whence xy = n 3 {x + y) — n 3 ,
or (x — n 3 ) {y — n 3 ) — n 3 (n 3 — 1 ).
An obvious solution is
x — n 3 = n 3 — 1, y — n 3 = n 3 ,
which gives z — 2n 3 —l + 2n 3 — 1 = 4% 3 — 2, so that
u = nz — n(4n 3 —2).
II. The second is a similar problem about two rectangles,
equivalent to the solution of the equations
(1) x + y = u + v)
(2) xy =n.uvj
and the solution given in the text is
x + y = u + v = n 3 —l, (3)