如果x=300,则xx−3-x+6x2−3x+1x的值为(  ) A.0 B.101990 C.111110 D.101100

问题描述:

如果x=300,则

x
x−3
-
x+6
x2−3x
+
1
x
的值为(  )
A. 0
B.
101
990

C.
111
110

D.
101
100

原式=

x
x−3
-
x+6
x(x−3)
+
1
x

=
x2
x(x−3)
-
x+6
x(x−3)
+
x−3
x(x−3)

=
x2−x−6+x−3
x(x−3)

=
x2−9
x(x−3)

=
(x−3)(x+3)
x(x−3)

=
x+3
x

当x=300时,原式=
303
300
=
101
100

故选D.