题目内容
递等式计算(能简算的要简算)
-(
+
)
+
-
+
999.3-998.2+997.3-996.2+…+3.3-2.2+1.3-0.2
+
+
+
+
+
+
+
.
| 8 |
| 9 |
| 1 |
| 18 |
| 7 |
| 9 |
| 2 |
| 3 |
| 6 |
| 7 |
| 2 |
| 3 |
| 6 |
| 7 |
999.3-998.2+997.3-996.2+…+3.3-2.2+1.3-0.2
| 7 |
| 6 |
| 13 |
| 12 |
| 21 |
| 20 |
| 31 |
| 30 |
| 43 |
| 42 |
| 57 |
| 56 |
| 73 |
| 72 |
| 91 |
| 90 |
(1)
-(
+
),
=
-
-
,
=
-
-
,
=
-
,
=
;
(2)
+
-
+
,
=(
-
)+(
+
),
=0+
,
=
;
(3)999.3-998.2+997.3-996.2+…+3.3-2.2+1.3-0.2,
=(999.3-998.2)+(997.3-996.2)+…+(3.3-2.2)+(1.3-0.2),
=1.1+1.1+…+1.1(500个1.1),
=1.1×500,
=550;
(4)
+
+
+
+
+
+
+
,
=1+1+1+1+1+1+1+1+
+
+
+
+
+
+
+
,
=8+
-
+
-
+…+
-
,
=8+
-
,
=8
.
| 8 |
| 9 |
| 1 |
| 18 |
| 7 |
| 9 |
=
| 8 |
| 9 |
| 1 |
| 18 |
| 7 |
| 9 |
=
| 8 |
| 9 |
| 7 |
| 9 |
| 1 |
| 18 |
=
| 1 |
| 9 |
| 1 |
| 18 |
=
| 1 |
| 18 |
(2)
| 2 |
| 3 |
| 6 |
| 7 |
| 2 |
| 3 |
| 6 |
| 7 |
=(
| 2 |
| 3 |
| 2 |
| 3 |
| 6 |
| 7 |
| 6 |
| 7 |
=0+
| 12 |
| 7 |
=
| 12 |
| 7 |
(3)999.3-998.2+997.3-996.2+…+3.3-2.2+1.3-0.2,
=(999.3-998.2)+(997.3-996.2)+…+(3.3-2.2)+(1.3-0.2),
=1.1+1.1+…+1.1(500个1.1),
=1.1×500,
=550;
(4)
| 7 |
| 6 |
| 13 |
| 12 |
| 21 |
| 20 |
| 31 |
| 30 |
| 43 |
| 42 |
| 57 |
| 56 |
| 73 |
| 72 |
| 91 |
| 90 |
=1+1+1+1+1+1+1+1+
| 1 |
| 6 |
| 1 |
| 12 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 42 |
| 1 |
| 56 |
| 1 |
| 72 |
| 1 |
| 90 |
=8+
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 9 |
| 1 |
| 10 |
=8+
| 1 |
| 2 |
| 1 |
| 10 |
=8
| 2 |
| 5 |
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