Question

先化简,再求值:(1-x+1分之1)/x-1分之x,其中x=2

怎么做

Answer 1

上面:(1-分之1)=（x+1分之x+1）+1分之1=x/（x+1）
下面：x-1分之x
化简上下：（x-1）/（x+1）
把x=2带入的 x=1/3

Answer 2

=[(x+1)/(x+1)-1/(x+1)]×(x-1)/x
=x/(x+1)×(x-1)/x
=(x-1)/(x+1)
当x=2时，原式=(2-1)/(2+1)=1/3

Answer 3

(1-1/(x+1))/(x/(x-1))
=(x/(x+1))/(x/(x-1))
=(x-1)/(x+1)
=1/3

Answer 4

解：原式=x/(x+1)×(x²-1)/x;
=x-1;
∴x=2