172
ON A SYSTEM OF ALGEBRAIC EQUATIONS.
[256
where a = v — c 2 . The equation in c 2 is thus of the fourth order; and in like manner,
if instead of c 2 we take <r as the unknown quantity, and substitute therefore for c 2
its value v — cr, the equation in a will be also of the fourth order: and effecting the
reduction, this equation is
8a- 4 — 12ikt 3 + (6v 2 — 2A./a) a 2 + (A, 3 + f — v 3 — Xpv) a + (vX — /a 2 ) (v/u, — X 2 ) = 0.
It may be remarked that if a = 0, then a or b vanishes; and therefore, from the
original equations, vX — /a 2 = 0, or vg — A 2 = 0, which agrees with the result afforded by
the foregoing equation in cr. Again, if a = v, then c = 0; and therefore, from the
original equations, v' 2 — X/a = 0. The left-hand side of the equation in a, writing therein
a = v, should therefore contain the factor v 2 — A/a ; its value in fact is v 4 — 2A/ai> 2 -I- A,'ta 2 ,
or (v 2 — Ayu,) 2 .
vC 'll
If in the original equations we write a = -, b = -,
the equations become
a? + cyz — A.z 2 = 0,
if + czx — fjbz 2 = 0,
(c 2 — v)z 2 + xy = 0,
which are three homogeneous equations of the second order; from which, if the
variables x, y, z are eliminated, we have the required equation in c. And it would
not, I think, be difficult, from the known formula for the general case, to deduce the
foregoing result corresponding to the very particular case which is here in question.
2, Stone Buildings, W.C., September 25, 1860.