问题:
若x=
1
2
(
a
+
b
),y=
1
2
(
a
-
b
),则x+y的值为______.
若x=
(
+
),y=
(
-
),则x+y的值为______.
1 |
2 |
a |
b |
1 |
2 |
a |
b |
参考答案: