计算: (1)-4.2+5.7-8.4+10; (2)6.1-3.7-4.9+1.8; (3)1/3-2/3+1; (4)-1/4+5/6+2/3-1/2.

问题描述:

计算:
(1)-4.2+5.7-8.4+10;   (2)6.1-3.7-4.9+1.8;
(3)

1
3
-
2
3
+1;            (4)-
1
4
+
5
6
+
2
3
-
1
2

(1)原式=(10+5.7)-(4.2+8.4),
=15.7-12.6,
=3.1;
(2)原式=(6.1+1.8)-(3.7+4.9),
=7.9-8.6,
=-0.7;
(3)原式=-

1
3
+1=
2
3

(4)原式=(
5
6
+
2
3
)-(
1
4
+
1
2
),
=
3
2
-
3
4

=
3
4