下面各题怎样算简便就怎样算. ( 4 15 - 1 25 )×15×25 1 2 + 3

2024-12-17 07:24:11
推荐回答(1个)
回答1:

(1)(
4
15
-
1
25
)×15×25,
=
4
15
×15×25-
1
25
×25×15,
=100-15,
=85;

(2)
1
2
+
3
4
+
7
8
+
15
16
+
31
32
+
63
64
+
127
128

=(1-
1
2
)+(1-
1
4
)+(1-
1
8
)+…+(1-
1
128
),
=7-(
1
2
+
1
4
+
1
8
+
1
16
+
1
32
+
1
64
+
1
128
),
=7-(1-
1
2
+
1
2
-
1
4
+
1
4
-
1
8
+
1
8
-
1
16
+
1
16
-
1
32
+
1
32
-
1
64
+
1
64
-
1
128
),
=7-(1-
1
128
),
=6+
1
128

=6
1
128