B. TÍNH XLIM→−∞(3 X3+2X2+ −1 4X2 +2X+ +3 MX)NẾU M= −3 THÌ XLIM→−∞...
Câu 1b.
Tínhx
lim→−∞
(
3
x3
+2x2
+ −1 4x2
+2x+ +3 mx)
Nếu m= −3 thìx
lim→−∞
(
3
x3
+2x2
+ −1 4x2
+2x+ +3 mx)
(
3
3
2
2
)
lim ( 2 1 ) ( 4 2 3 2 )=→−∞
+ + − − + + +x
x x x x x xTa cóx
lim→−∞
(
3
x3
+2x2
+ − =1 x)
x
lim→−∞
3
(x3
+2x2
+1)2
+2xx2
3
+(1x3
+2x2
+1)2
+x2
= 23(
2
)
2
2 3 1+ −x x x x+ + + = =lim 4 2 3 2 lim+ + −→−∞
→−∞
4 2 3 2 2x
x
x x xSuy rax
lim→−∞
(
3
x3
+2x2
+ −1 4x2
+2x+ +3 mx)
=76Nếu m< −3 thìx
lim→−∞
(
3
x3
+2x2
+ −1 4x2
+2x+ +3 mx)
lim ( 2 1 ) ( 4 2 3 2 ) ( 3)=→−∞
+ + − − + + + + + = +∞x
x x x x x x m xNếu m> −3 thìx
lim→−∞
(
3
x3
+2x2
+ −1 4x2
+2x+ +3 mx)
=→−∞
+ + − − + + + + + = −∞2
1
3
1
C C C C