21
5
÷7×
5
9
15
2
×4÷
25
7
4
5
×
10
3
-
4
5
×
10
3
(1-
2
3
×
3
5
5
6
7
8
÷
3
8
-
1
8
÷
3
8
1
4
×
26
9
×
4
13
分析:此題考查在混合運(yùn)算中有括號(hào)時(shí),要先算括號(hào)里面的,再算括號(hào)外面的.
解答:解:
21
5
÷7×
5
9
,
=
3
5
×
5
9
,
=
1
3
;
15
2
×4÷
25
7

=30×
7
25

=
42
5
;
4
5
×
10
3
-
4
5
×
10
3
,
=0;
(1-
2
3
×
3
5
)×
5
6
,
=(1-
2
5
)×
5
6
,
=
1
2
;
7
8
÷
3
8
-
1
8
÷
3
8
,
=
7
3
-
1
3

=2,
1
4
×
26
9
×
4
13
,
=
1
3
點(diǎn)評(píng):解決關(guān)鍵是在混合運(yùn)算中,要按照運(yùn)算順序進(jìn)行計(jì)算.
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