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Mathematics
Mathematics
Problem
4. Determine the set of all real numbers
x
x
x
for which
f
(
x
)
=
arccos
(
x
2
−
4
5
)
f(x)=\arccos\!\left(\dfrac{x^{2}-4}{5}\right)
f
(
x
)
=
arccos
(
5
x
2
−
4
)
is defined. a)
(
−
3
,
3
)
(-3,\,3)
(
−
3
,
3
)
b)
[
−
3
,
3
]
[-3,\,3]
[
−
3
,
3
]
c) \bigl[-\sqrt{5},\,\sqrt{5}\bigr] d)
(
−
∞
,
−
3
]
∪
[
3
,
∞
)
(-\infty,-3] \cup [3,\infty)
(
−
∞
,
−
3
]
∪
[
3
,
∞
)
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