6 + 7 - 21 = 7 + 6 - 21- = - 4 =+ = 0 =+1 - 1-
2
- 6 + 7 - 21 = 2
- 7 + 6 - 21
-
= - 4
=
+ = 0
=
+1
- 1
-
:
+
- 1
- 1
- 1
S u t m: OÀN TI N TRUNG - THCS Hoàng V n Th - N
(
(
+1)( -
- 1)(
+ 1)
+1)
-
- 1
- 1
:
(
- 1
- 1)
+
-1
2
- 6 + 7 - 21 = 2
- 7 + 6 - 21
-
= - 4
=
+ = 0
=
+1
- 1
-
:
+
- 1
- 1
- 1
S u t m: OÀN TI N TRUNG - THCS Hoàng V n Th - N
(
(
+1)( -
- 1)(
+ 1)
+1)
-
- 1
- 1
:
(
- 1
- 1)
+
-1