4 Group 7
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Question 1.
The derivative of function
f
(
x
)
=
x
arccos
x
-
1
-
x
2
is
a)
f
′
(
x
)
=
arccos
x
b)
f
′
(
x
)
=
arccos
x
-
1
1
-
x
2
c)
f
′
(
x
)
=
arccos
x
+
1
-
x
2
d)
f
′
(
x
)
=
arccos
x
+
arcsin
x
1
-
x
2
e)
f
′
(
x
)
=
x
arcsin
x
Question 2.
The radius
r
of a circle is changing with a velocity
v
. Its circumference is changing with the velocity
a)
4
π
r
v
2
b)
4
π
r
v
c)
2
π
v
d)
2
π
r
v
e)
π
r
v
Question 3.
The maximal interval on which the function
f
(
x
)
=
4
-
x
2
is concave, is
a)
(
0
,
2
)
b)
(
-
∞
,
+
∞
)
c)
⟨
-
2
,
2
⟩
d)
(
-
4
,
4
)
e)
(
-
2
,
0
)
Evaluate