问题 解答题
简便计算.
①31.9×18-8×31.9

13
14
-
13
15
+
1
14
-
2
15

2
5
×1.4+
2
5
答案

①31.9×18-8×31.9,

=31.9×(18-8),

=31.9×10,

=319;

13
14
-
13
15
+
1
14
-
2
15

=(

13
14
+
1
14
)-(
2
15
+
13
15
),

=1-1,

=0;

2
5
×1.4+
2
5

=(1.4+1)×0.4,

=2.4×0.4,

=0.96.

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