题目内容
计算
①78÷[32×(1-
)+3.6]
②
÷[(
-
)÷
]
③
×0.625+
×
+6.13+
④
+
+
+
+
+
⑤
+
+
+
+
⑥(1+
+
)×(
+
+
)-(1+
+
+
)×(
+
)
解:
①78÷[32×(1-
)+3.6],
=78÷[32×
+3.6],
=78÷[12+3.6],
=78÷15.6,
=5;
②
÷[(
-
)÷
],
=
÷[
÷
],
=
÷
,
=
;
③
×0.625+
×
+6.13+
,
=
×
+
×
+6.13+
,
=(
+
)×
+6.13+
,
=
×
+6.13+
,
=
+6.13+
,
=
+
+6.13,
=1+6.13,
=7.13;
④
+
+
+
+
+
,
=(
+
)+(
+
)+(
+
),
=
+
+
,
=1+
,
=1
;
⑤
+
+
+
+
,
=
×(
-
+
-
+
-
+
-
+
-
),
=
×(
-
),
=
×
,
=
;
⑥(1+
+
)×(
+
+
)-(1+
+
+
)×(
+
),
=1×(
+
+
)+(
+
)×(
+
+
)-1×(
+
)-(
+
+
)×(
+
),
=
+
+
+(
+
)×(
+
+
)-(
+
)-(
+
+
)×(
+
),
=
+
+
-(
+
)+[(
+
)×(
+
+
)-(
+
+
)×(
+
)],
=
+
+
-
-
,
=
.
分析:①先算减法,再算乘法,再算加法,最后算除法;
②先算减法,再算中括号里面的除法,最后算括号外面的除法;
③根据乘法分配律进行计算;
④根据加法交换律和结合律进行计算;
⑤根据分数的拆项进行计算;
⑥把(
+
),(
+
+
),分别看作一个整体,再根据乘法分配律进行计算.
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.
①78÷[32×(1-

=78÷[32×

=78÷[12+3.6],
=78÷15.6,
=5;
②




=



=


=

③




=





=(




=



=


=


=1+6.13,
=7.13;
④






=(






=



=1+

=1

⑤





=











=



=


=

⑥(1+










=1×(















=















=















=





=

分析:①先算减法,再算乘法,再算加法,最后算除法;
②先算减法,再算中括号里面的除法,最后算括号外面的除法;
③根据乘法分配律进行计算;
④根据加法交换律和结合律进行计算;
⑤根据分数的拆项进行计算;
⑥把(





点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.

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