问题
解答题
计算,写出必要过程.
2008×98
1+2-3+4+5-6+7+8-9+…+601+602-603+604+605-606. |
答案
①
:x=29 2
:0.5,4 7
2
x=4 7
×0.5,9 2
2
x=4 7
,9 4
x=
;7 8
②
÷(2
+35 9
-5.229 10 2
-65 9
+5.2227 50
+2006×0.4 2008×0.5
),1.6 2008
=
÷2
-1.325 9 2
-1.325 9
,1606.4 2008
=
,20080 16064
=
;1255 1004
③2008×98
-225×101 4
+2001 25
×284 5
,3 4
=2008×
-225×393 4
+251 25
×1004 5
,115 4
=197286-2259+5773,
=200800;
④1+2-3+4+5-6+7+8-9+..+601+602-603+604+605-606,
=(1+2-3)+(4+5-6)+(7+8-9)+…(604+605-606),
=0+3+6+9+…+603,
=(0+603)×202÷2,
=60903.