问题
解答题
|
答案
原式=
+
×41 2 (1+
)×41 2
+…+
×61 3
×3 2
×64 3
,
×1999×21 1999
×3 2
×…×4 3
×1999×22000 1999
=
+2 2×3
+…+2 3×4
,2 1999×2000
=(
-1 2
+1 3
-1 3
+…+1 4
-1 1999
)×2,1 2000
=(
-1 2
)×2,1 2000
=1-
,1 1000
=
.999 1000