NOTE ON THE TRANSFORMATION OF TWO SIMULTANEOUS
EQUATIONS.
[From the Quarterly Journal of Pure and Applied Mathematics, vol. XI. (1871), pp. 266, 267.]
Writing in Mr Walton’s equations (1) and (2)
a b c a /3 y
S’ d } d’ 8’ 8* 8
instead of a, b, c, a, ¡3, y respectively; and putting for shortness
A = by—c/3, F — a,8 — da,
B = ca — ay, G —b8 — d/3,
C = a/3 — bu, H = c8 — dy,
the equations become
a (b — c) b (c — a) c(a — b) _
F + G + ’
« (0 - 7) , 0 (7 “ a ) , 7 (a - 0) __ 0
r~ + 0 ii
Multiplying by FGH and effecting some obvious transformations, the equations become
whence also
aAF+ bBG+cCH = 0]
(18)
aAF+ßBG + yCH = 0j
AF 2 + BG*+ CH* — 0
(19)-
Now regarding (a, /3, 7, 0) as the coordinates of a point in space, the equations
(18) and (19) represent each of them a cone having for vertex the point a : /3 : 7 : 8
= a : b : c : d, viz. (18) is a quadric cone, (19) a cubic cone; they intersect therefore
in six lines; and it may
be shown that these
are
the line
a : ß
: y = a
: b :
: c
(twice) 2
0 : 7 :
8 = b
: c :
: d
1
})
7 : a :
8 — c
: a :
: d
1
?>
a : 0 :
: 8 = a
: b :
; d
1
» 0-1'
7 — a : a — ß
: 8 = b
— c :
c — a :
: a — b : d 1
6,
agreeing with Mr Walton’s result.