计算(写出主要过程,其中第①④题简算) ①3.6-2.8+7.4-7.2 ②(1-0.05)÷1.9+0.1 ③4/29×[1-(3/4-3/8)] ④8/17÷23+1/23×9/17.

问题描述:

计算(写出主要过程,其中第①④题简算) 
①3.6-2.8+7.4-7.2
②(1-0.05)÷1.9+0.1

4
29
×[1-(
3
4
-
3
8
)]
8
17
÷23+
1
23
×
9
17

①3.6-2.8+7.4-7.2
=(3.6+7.4)-(2.8+7.2)
=11-10
=1;
②(1-0.05)÷1.9+0.1
=0.95÷1.9+0.1
=0.5+0.1
=0.6;

4
29
×[1-(
3
4
-
3
8
)]
=
4
29
×[1-
3
8
]
=
4
29
×
5
8

=
5
58

8
17
÷23+
1
23
×
9
17

=(
8
17
+
9
17
)×
1
23

=1×
1
23

=
1
23