已知:xy/x+y=a,xz/x+z=b,yz/y+z=c,且abc≠0,求x的值.

问题描述:

已知:

xy
x+y
=a,
xz
x+z
=b
yz
y+z
=c
,且abc≠0,求x的值.

xy
x+y
=a,
xz
x+z
=b
yz
y+z
=c

x+y
xy
=
1
a
x+z
xz
=
1
b
y+z
yz
=
1
c

1
a
=
1
x
+
1
y
①,
1
b
=
1
x
+
1
z
②,
1
c
=
1
y
+
1
z
③,
①+②-③得
1
a
+
1
b
1
c
=
2
x

∴x=
2abc
bc+ac−ab