题目内容
怎样算简便就怎样算.
①9+8÷26+27÷39
②0.8×[13-(3.12+5.28 )]
③
÷[
-(
-
)]
④
+(
+
)×
+
.
①9+8÷26+27÷39
②0.8×[13-(3.12+5.28 )]
③
| 4 |
| 9 |
| 4 |
| 5 |
| 1 |
| 3 |
| 1 |
| 5 |
④
| 6 |
| 17 |
| 13 |
| 14 |
| 13 |
| 17 |
| 11 |
| 13 |
| 3 |
| 14 |
分析:①先把除法算式化成分数再运用加法的结合律进行计算.
②③按照四则混合运算的顺序计算即可.
④先运用乘法的分配律进行计算,再运用加法的结合律、交换律进行计算.使计算更加简便.
②③按照四则混合运算的顺序计算即可.
④先运用乘法的分配律进行计算,再运用加法的结合律、交换律进行计算.使计算更加简便.
解答:解:①9+8÷26+27÷39,
=9+
+
,
=9+
+
,
=9+(
+
),
=10;
②0.8×[13-(3.12+5.28 )],
=0.8×[13-8.4],
=0.8×4.6,
=3.68;
③
÷[
-(
-
)],
=
÷[
+
-
],
=
÷
,
=
×
,
=
;
④
+(
+
)×
+
,
=
+
×
+
×
+
,
=
+
+
+
,
=(
+
)+(
+
),
=1+1,
=2.
=9+
| 8 |
| 26 |
| 27 |
| 39 |
=9+
| 4 |
| 13 |
| 9 |
| 13 |
=9+(
| 4 |
| 13 |
| 9 |
| 13 |
=10;
②0.8×[13-(3.12+5.28 )],
=0.8×[13-8.4],
=0.8×4.6,
=3.68;
③
| 4 |
| 9 |
| 4 |
| 5 |
| 1 |
| 3 |
| 1 |
| 5 |
=
| 4 |
| 9 |
| 4 |
| 5 |
| 1 |
| 5 |
| 1 |
| 3 |
=
| 4 |
| 9 |
| 2 |
| 3 |
=
| 4 |
| 9 |
| 3 |
| 2 |
=
| 2 |
| 3 |
④
| 6 |
| 17 |
| 13 |
| 14 |
| 13 |
| 17 |
| 11 |
| 13 |
| 3 |
| 14 |
=
| 6 |
| 17 |
| 13 |
| 14 |
| 11 |
| 13 |
| 13 |
| 17 |
| 11 |
| 13 |
| 3 |
| 14 |
=
| 6 |
| 17 |
| 11 |
| 14 |
| 11 |
| 17 |
| 3 |
| 14 |
=(
| 6 |
| 17 |
| 11 |
| 17 |
| 11 |
| 14 |
| 3 |
| 14 |
=1+1,
=2.
点评:本题考查了乘法分配律及加法交换律、结合律的灵活运用.
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