a)
x
=
+
n
tai
x
=
+
n
; b)
x
=
n
tai
x
=
±
+
n
; c)
x
=
+
n
tai
x
=
n
2
tai
x
=
-
+
n
2
; d)
x
=
n
tai
x
=
+
n
tai
x
=
+
n
; e)
x
=
+
n
2
tai
+
n
2
<
x
<
+
n
2
;
n
.