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Mathematics
Mathematics
Problem
Let
f
f
f
be twice differentiable with
f
′
(
x
)
=
x
2
−
4
f'(x)=x^{2}-4
f
′
(
x
)
=
x
2
−
4
and
f
′
′
(
x
)
=
2
x
f''(x)=2x
f
′′
(
x
)
=
2
x
. Which of the following intervals consists entirely of points where
f
f
f
is increasing and concave down? a)
(
2
,
∞
)
(2,\infty)
(
2
,
∞
)
b)
(
−
2
,
0
)
(-2,0)
(
−
2
,
0
)
c)
(
−
∞
,
−
2
)
(-\infty,-2)
(
−
∞
,
−
2
)
d)
(
−
∞
,
−
2
)
(-\infty,-\sqrt{2})
(
−
∞
,
−
2
)
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