问题 解答题
已知a、b、c为实数,
ab
a+b
=
1
6
bc
b+c
=
1
8
ca
c+a
=
1
10
.求分式
abc
ab+bc+ca
的值.
答案

ab
a+b
=
1
6
bc
b+c
=
1
8
ca
c+a
=
1
10

a+b
ab
=6,
b+c
bc
=8,
c+a
ca
=10,

1
b
1
a
=6
1
c
+
1
b
=8
1
a
+
1
c
=10

1
a
=4,
1
b
=2,
1
c
=6,

1
a
+
1
b
+
1
c
=
bc+ac+ab
abc
=12,

abc
ab+bc+ca
=
1
12

单项选择题
单项选择题 A1/A2型题