问题 解答题
0.7×1
4
9
+2
3
4
×l5+0.7×
5
9
+
1
4
×l5.
答案

0.7×1

4
9
+2
3
4
×l5+0.7×
5
9
+
1
4
×l5,

=(0.7×1

4
9
+0.7×
5
9
)+(2
3
4
×15+
1
4
×15),

=(1

4
9
+
5
9
)×0.7+(2
3
4
+
1
4
)×15,

=2×0.7+3×15,

=1.4+45,

=46.4.

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