Question

（

1

x

-

x-3

1-x

+

2

x2-x

）÷（1+

3

x

-

4

x2

）

Answer 1

(

1

x

-

x-3

1-x

+

2

x2-x

)÷(1+

3

x

-

4

x2

)
=

(x-1)+(x-3)x+2

x(x-1)

÷

x2+3x-4

x2

=

x2-2x+1

x(x-1)

×

x2

x2+3x-4

=

x

x+4

．
故答案为

x

x+4

．