题目内容
怎样简便怎样算.
(1)(
+
)×
(2)[12×(
+
)]÷
(3)
×
×
(4)
×11+
(5)86×
=
(1)(
| 5 |
| 8 |
| 5 |
| 6 |
| 4 |
| 25 |
(2)[12×(
| 2 |
| 3 |
| 1 |
| 4 |
| 11 |
| 12 |
(3)
| 1 |
| 3 |
| 7 |
| 16 |
| 3 |
| 7 |
(4)
| 11 |
| 12 |
| 11 |
| 12 |
(5)86×
| 2 |
| 85 |
分析:(1)(4)运用乘法分配律简算;
(2)先算小括号内的,再算中括号内的,最后算括号外的;
(3)约分计算;
(5)把86看作85+1,运用乘法分配律简算.
(2)先算小括号内的,再算中括号内的,最后算括号外的;
(3)约分计算;
(5)把86看作85+1,运用乘法分配律简算.
解答:解:(1)(
+
)×
,
=
×
+
×
,
=
+
,
=
;
(2)[12×(
+
)]÷
,
=[12×
]÷
,
=11×
,
=12;
(3)
×
×
=
;
(4)
×11+
,
=
×(11+1),
=
×12,
=11;
(5)86×
,
=(85+1)×
,
=2+
,
=2
.
| 5 |
| 8 |
| 5 |
| 6 |
| 4 |
| 25 |
=
| 5 |
| 8 |
| 4 |
| 25 |
| 5 |
| 6 |
| 4 |
| 25 |
=
| 1 |
| 10 |
| 2 |
| 15 |
=
| 7 |
| 30 |
(2)[12×(
| 2 |
| 3 |
| 1 |
| 4 |
| 11 |
| 12 |
=[12×
| 11 |
| 12 |
| 11 |
| 12 |
=11×
| 12 |
| 11 |
=12;
(3)
| 1 |
| 3 |
| 7 |
| 16 |
| 3 |
| 7 |
| 1 |
| 16 |
(4)
| 11 |
| 12 |
| 11 |
| 12 |
=
| 11 |
| 12 |
=
| 11 |
| 12 |
=11;
(5)86×
| 2 |
| 85 |
=(85+1)×
| 2 |
| 85 |
=2+
| 2 |
| 85 |
=2
| 2 |
| 85 |
点评:此题考查了分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
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