lim
x
→
3
=
2
x
2
-
2
x
-
12
x
2
+
4
x
-
21
lim
x
→
3
=
2
x
2
-
2
x
-
12
x
2
+
4
x
-
21
(1)
⇒
lim
x
→
3
=
(
x
-
3
x
+
2
x
+
7
(
x
-
3
=
x
+
2
x
+
7
lim
x
→
3
=
(
3
+
2
3
+
7
=
lim
x
→
3
=
1
2
⇒
lim
x
→
3
=
(
x
-
3
x
+
2
x
+
7
(
x
-
3
=
x
+
2
x
+
7
lim
x
→
3
=
(
3
+
2
3
+
7
=
lim
x
→
3
=
1
2
(2)