Question

先化簡代數(shù)式

x2-2x

x2-1

÷(x-1-

2x-1

x+1

)，然后選取一個(gè)你喜歡的數(shù)代入，求原代數(shù)式的值．

Answer 1

x2-2x

x2-1

÷(x-1-

2x-1

x+1

)
=

x(x-2)

(x-1)(x+1)

÷[

(x-1)(x+1)

x+1

-

2x-1

x+1

]
=

x(x-2)

(x-1)(x+1)

÷

x2-1-2x+1

x+1

=

x(x-2)

(x-1)(x+1)

×

x+1

x(x-2)

=

1

x-1

，
只要x≠1，-1，2，隨便取一個(gè)數(shù)代入即可；
當(dāng)x=3時(shí)，
原式=

1

x-1

=

1

2

．