(
ax
+
by
+
c
)
dx
+
(
px
+
qy
+
r
)
dy
=
0
0
,
,
,
,
,
b
c
p
q
r
≠
a
,
b
,
c
,
p
,
q
,
r
≠
0
! "
m c
r b
q a
p
= =
=
(
ax
+
by
+
c
)
dx
+
m
(
ax
+
by
+
c
)
dy
=
0
! "
0
#
$ %
& $ ! ' "
(
(
)
(
)
0
2
2
2
1
+
+
+
=
+
+
y
dx
x
y
dy
"
) $ ' " ' " $ $
c r b
q a
p
≠
= m
b q a
p
= =
(
ax
+
by
+
c
)
dx
+
(
m
(
ax
+
by
)
+
r
)
dy
=
0
by ax
u = +
#
$ *
& $ ! ' "
$
%-$ ' " ' " $ $a b c
≠ ≠
r qy px
v
c by ax
u
+ +
=
+ +
=
# $ -. "
( /