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Byju's Answer
Standard XII
Mathematics
First Derivative Test for Local Maximum
Let gi: [π8, ...
Question
Let
g
i
:
[
π
8
,
3
π
8
]
→
R
,
i
=
1
,
2
and
f
:
[
π
8
,
3
π
8
]
→
R
be functions such that
g
1
(
x
)
=
1
,
g
2
(
x
)
=
|
4
x
−
π
|
and
f
(
x
)
=
sin
2
x
,
for all
x
∈
[
π
8
,
3
π
8
]
.
Define
S
i
=
∫
3
π
8
π
8
f
(
x
)
⋅
g
i
(
x
)
d
x
,
i
=
1
,
2
The value of
16
S
1
π
is
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Solution
S
1
=
∫
3
π
8
π
8
sin
2
x
d
x
=
1
2
∫
3
π
8
π
8
(
1
−
cos
2
x
)
d
x
=
1
2
[
x
−
sin
2
x
2
]
3
π
8
π
8
S
1
=
1
2
[
(
3
π
4
−
1
2
√
2
)
−
(
π
8
−
1
2
√
2
)
]
=
π
8
⇒
16
S
1
π
=
16
π
×
π
8
=
2
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Similar questions
Q.
Let
g
i
:
[
π
8
,
3
π
8
]
→
R
,
i
=
1
,
2
and
f
:
[
π
8
,
3
π
8
]
→
R
be functions such that
g
1
(
x
)
=
1
,
g
2
(
x
)
=
|
4
x
−
π
|
and
f
(
x
)
=
sin
2
x
,
for all
x
∈
[
π
8
,
3
π
8
]
.
Define
S
i
=
∫
3
π
8
π
8
f
(
x
)
⋅
g
i
(
x
)
d
x
,
i
=
1
,
2
The value of
48
S
2
π
2
is
Q.
Let
f
(
x
)
=
sin
4
x
+
cos
4
x
. Then
f
is an increasing function in the interval :
Q.
Let
f
:
(
0
,
π
)
→
R
be a twice differentiable function such that
lim
t
→
x
f
(
x
)
sin
t
−
f
(
t
)
sin
x
t
−
x
=
sin
2
x
for all
x
ϵ
(
0
,
π
)
.
If
f
(
π
6
)
=
−
π
12
, then which of the following statement(s) is (are) TRUE?
Q.
Let
f
:
(
0
,
π
)
→
R
be a twice differentiable function such that
lim
t
→
x
f
(
x
)
sin
t
−
f
(
t
)
sin
x
t
−
x
=
sin
2
x
for all
x
∈
(
0
,
π
)
.
If
f
(
π
6
)
=
−
π
12
, then which of the following statement(s) is (are) TRUE?
Q.
The function
f
(
x
)
=
sin
2
x
+
cos
2
x
∀
x
∈
[
0
,
π
2
]
is strictly decreasing in the interval
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