题目内容
解:
(1)
,
=
÷42,
=2÷42,
=
;
(2)
,
=
,
=
×1,
=
;
(3)
,
=
÷[
×
],
=
÷
,
=
;
(4)
,
=81+
,
=81
;
(5)
,
=
×[(
+
)×24],
=
×[
×24+
×24],
=
×[20+9],
=
×29,
=1;
(6)
,
=[
-
]×
,
=
×
,
=
.
分析:(1)根据乘法交换律进行简算;
(2)根据乘法分配律进行简算;
(3)先算加法,再算乘法,最后算除法;
(4)先算除法,再算加法;
(5)中括号里面的根据乘法分配律进行简算,最后算乘法;
(6)先算小括号里面的减法,再算中括号里面的减法,最后算乘法.
点评:此题主要考查分数的四则混合运算的运算顺序和应用运算定律进行简便计算.
(1)
=
=2÷42,
=
(2)
=
=
=
(3)
=
=
=
(4)
=81+
=81
(5)
=
=
=
=
=1;
(6)
=[
=
=
分析:(1)根据乘法交换律进行简算;
(2)根据乘法分配律进行简算;
(3)先算加法,再算乘法,最后算除法;
(4)先算除法,再算加法;
(5)中括号里面的根据乘法分配律进行简算,最后算乘法;
(6)先算小括号里面的减法,再算中括号里面的减法,最后算乘法.
点评:此题主要考查分数的四则混合运算的运算顺序和应用运算定律进行简便计算.
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