liqixuan
幼苗
共回答了12个问题采纳率:100% 举报
(1)2-(6÷0.5-3×3)÷5+5×0.8,
=2-(12-9)÷5+5×0.8,
=2-3÷5+5×0.8,
=2-0.6+4,
=1.4+4,
=5.4;
(2)4
3
8 ×(
2
5 +
1
6 -
3
7 )÷
1
48 ,
=4
3
8 ×(
2
5 +
1
6 -
3
7 )×48,
=4
3
8 ×48×(
2
5 +
1
6 -
3
7 ),
=210×(
2
5 +
1
6 -
3
7 ),
=210×
2
5 +210×
1
6 -210×
3
7 ,
=84+35-90,
=119-90,
=29;
(3)1.25×3.45×6.789+3.75×1.15×1.211,
=4.3125×6.789+4.3125×1.211,
=4.3125×(6.789+1.211),
=4.3125×8,
=34.5;
(4)
1
11×13 +
1
13×15 +
1
15×17 +
1
17×19 ,
=
1
2 ×(
1
11 -
1
13 )+
1
2 ×(
1
13 -
1
15 )+
1
2 ×(
1
15 -
1
17 )+
1
2 ×(
1
17 -
1
19 ),
=
1
2 ×(
1
11 -
1
13 +
1
13 -
1
15 +
1
15 -
1
17 +
1
17 -
1
19 ),
=
1
2 ×(
1
11 -
1
19 ),
=
1
2 ×
8
209 ,
=
4
209 .
1年前
4