若x,y为实数,且y=x2−4+4−x2+1x+2,求x+y的值.

问题描述:

若x,y为实数,且y=

x2−4
+
4−x2
+1
x+2
,求
x+y
的值.

根据题意可得:x2-4≥0,4-x2≥0,x+2≠0,
∴x2-4=0,x≠-2,
解得:x=2,
y=

x2−4
+
4−x2
+1
x+2
=
1
4

x+y=
9
4

x+y
=
9
4
=
3
2

故答案为:
3
2