Question

已知

x+y

x-y

=3，則

x+y

x-y

-

3(x-y)

5(x+y)

=______．

Answer 1

∵

x+y

x-y

=3，
∴

x-y

x+y

=

1

3

，
∴

x+y

x-y

-

3(x-y)

5(x+y)

=3-

3

5

×

1

3

=2

4

5

．
故答案為2

4

5

．