(1)计算:1/x−1/x+1=_,1/x+1−1/x+2=_,1/x+2−1/x+3=_; (2)计算:1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+…+1/(x+2013)(x+2014),当x=1时,求该代数式

问题描述:

(1)计算:

1
x
1
x+1
=______,
1
x+1
1
x+2
=______,
1
x+2
1
x+3
=______;
(2)计算:
1
x(x+1)
+
1
(x+1)(x+2)
+
1
(x+2)(x+3)
+
+
1
(x+2013)(x+2014)
,当x=1时,求该代数式的值.

(1)

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

(2)原式=
1
x
-
1
x+1
+
1
x+1
-
1
x+2
+…+
1
x+2013
-
1
x+2014
=
1
x
-
1
x+2014
=
2014
x(x+2014)

当x=1时,原式=
2014
2015

故答案为:(1)
1
x(x+1)
1
(x+1)(x+2)
1
(x+2)(x+3)