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Question
Mathematics
The function f defined by f(x) =x3 - 3x2 + 5x + 7 ,is
Q. The function
f
defined by
f
(
x
)
=
x
3
−
3
x
2
+
5
x
+
7
,is
2190
215
JEE Main
JEE Main 2017
Application of Derivatives
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A
increasing in R.
36%
B
decreasing in R.
10%
C
decreasing in
(
0
,
∞
)
and increasing in
(
−
∞
,
0
)
.
21%
D
increasing in
(
0
,
∞
)
and decreasing in
(
−
∞
,
0
)
.
33%
Solution:
f
(
x
)
=
x
3
−
3
x
2
+
5
x
+
7
f
′
(
x
)
=
3
x
2
−
6
x
+
5
>
0
f
′
(
x
)
=
3
x
2
−
6
x
+
5
<
0
x
∈
ϕ