用简便方法计算: (1)−1.53×0.75+1.53×1/2+4/5×1.53 (2)(21/3−31/2+19/12)÷(−11/6).

问题描述:

用简便方法计算:
(1)−1.53×0.75+1.53×

1
2
+
4
5
×1.53
(2)(2
1
3
−3
1
2
+1
9
12
)÷(−1
1
6
)

(1)-1.53×0.75+1.53×

1
2
+
4
5
×1.53,
=1.53×(-0.75+0.5+0.8),
=1.53×(1.3-0.75),
=1.53×0.55,
=0.8415;
(2)(2
1
3
-3
1
2
+1
9
12
)÷(-1
1
6
),
=(
7
3
-
7
2
+
21
12
)×(-
6
7
),
=
7
3
×(-
6
7
)-
7
2
×(-
6
7
)+
21
12
×(-
6
7
),
=-2+3-
3
2

=3-3
1
2

=-
1
2