题目内容
| 脱式计算,能简算的要简算. ( | |
| 12×( | ( |
| 23- | [1-( |
解:(1)(
)÷
,
=(
)×24,
=24×
+
×24+
×24,
=6+3+
,
=9+
,
=10
;
(2)
×11-
×
-
×
,
=(
×11)-[
×(
+
)],
=(
×11)-(
×1),
=
-
,
=
;
(3)12×(
),
=12×
+12×
-12×
,
=8+3-2,
=9;
(4)(
)×12-36÷47,
=
×12+
×12-36÷47,
=1+
-
,
=1+(
-
),
=1+0,
=1;
(5)23-
×
÷
,
=23-
÷
,
=23-18,
=5;
(6)[1-(
)]÷
,
=[1-
]÷
,
=
÷
,
=
.
分析:(1)先把除法变成乘法,再运用乘法分配律简算;
(2)把后两部分的乘法运用乘法分配律简算;
(3)运用乘法分配律简算;
(4)先运用乘法分配律简算,再运用加法结合律简算;
(5)先算乘法,再算除法,最后算加法;
(6)先算小括号里面的加法,再算中括号里面的减法,最后算括号外的除法.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
=(
=24×
=6+3+
=9+
=10
(2)
=(
=(
=
=
(3)12×(
=12×
=8+3-2,
=9;
(4)(
=
=1+
=1+(
=1+0,
=1;
(5)23-
=23-
=23-18,
=5;
(6)[1-(
=[1-
=
=
分析:(1)先把除法变成乘法,再运用乘法分配律简算;
(2)把后两部分的乘法运用乘法分配律简算;
(3)运用乘法分配律简算;
(4)先运用乘法分配律简算,再运用加法结合律简算;
(5)先算乘法,再算除法,最后算加法;
(6)先算小括号里面的加法,再算中括号里面的减法,最后算括号外的除法.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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