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Mathematics
Mathematics
Problem
For
f
(
x
)
=
x
2
cos
4
x
f(x)=x^{2}\cos 4x
f
(
x
)
=
x
2
cos
4
x
, evaluate
f
′
(
π
4
)
f'\!\left(\dfrac{\pi}{4}\right)
f
′
(
4
π
)
. a)
−
π
4
-\dfrac{\pi}{4}
−
4
π
b)
−
π
2
-\dfrac{\pi}{2}
−
2
π
c)
π
2
\dfrac{\pi}{2}
2
π
d)
0
0
0
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