2004×2002/2003; (1/15+2/17)×15×17; 1/1×2+1/2×3+1/3×4+…+1/99×100.
问题描述:
2004×
|
(
|
|
答
(1)2004×
2002 2003
=(2003+1)×
2002 2003
=2003×
+1×2002 2003
2002 2003
=2002+
2002 2003
=2002
;2002 2003
(2)(
+1 15
)×15×17 2 17
=(
+1 15
)×(15×17)2 17
=
×15×17+1 15
×17×152 17
=17+30
=47;
(3)
+1 1×2
+1 2×3
+…+1 3×4
1 99×100
=1-
+1 2
-1 2
+1 3
-1 3
+…+1 4
-1 99
1 100
=1-
1 100
=
.99 100