题目内容
| 用递等式计算(能简算的要简算). | 2 |
| 36×( |
解:(1)
×
÷
,
=
×
×
,
=
;
(2)2
×
-4÷
,
=
×
-4×
,
=
-10,
=-9
;
(3)
×9+
÷
,
=
×9+
×9,
=(
+
)×9,
=1×9,
=9;
(4)
÷[(
-
)×1
],
=
÷[
×
],
=
÷
,
=
×10,
=2.5;
(5)36×(
+
-
),
=36×
+36×
-36×
,
=28+27-30,
=25;
(6)
×
+
+1
×
,
=(
+1+1
)×
,
=3×
,
=
.
分析:(1)把除法改为乘法,约分即可;
(2)先算除法和乘法,再算减法;
(3)把除法改为乘法,运用乘法分配律简算;
(4)先算小括号内的,再算中括号内的,最后算括号外的;
(5)(6)运用乘法分配律简算.
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进行简便计算.
=
=
(2)2
=
=
=-9
(3)
=
=(
=1×9,
=9;
(4)
=
=
=
=2.5;
(5)36×(
=36×
=28+27-30,
=25;
(6)
=(
=3×
=
分析:(1)把除法改为乘法,约分即可;
(2)先算除法和乘法,再算减法;
(3)把除法改为乘法,运用乘法分配律简算;
(4)先算小括号内的,再算中括号内的,最后算括号外的;
(5)(6)运用乘法分配律简算.
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进行简便计算.
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