Michelle Ma
MATH 139, Fall, 2008
Review problems on functions.
WeBWorK assignment ass1 due 09/25/2010 at 11:55pm EDT.
1.
(1 pt) Let
f
(
x
) =

3
+
2
x
3
+
x
,
x
6
=

3
.
f

1
(
y
) =
Note: The expected answer is a function and the variable you
use in your answer must be
y
.
For which value of
y
is
f

1
(
y
)
not deﬁned?
2.
(1 pt) The only solution of the equation
ln
(
x
)+
ln
(
x

10
) =
1
is
x
=
.
Note that you can include the symbol
e
in your answer as well
as any function that WeBWorK understands.
Hint: How can you get rid of those logs?
Food for thought: Why is this the only solution? If you seem to
have more than one solution, which of them makes sense in the
original equation?
More generally, if
f
(
x
) =
ln
(
x
)+
ln
(
x

10
)
,
x
>
10
,
then
f

1
(
y
) =
Remember to use
y
as the variable in the function.
3.
(1 pt) The equation sin
(
x
) =

1
√
2
has
solutions in
the range 0
<
x
<
40.
The smallest of these solutions is
x
=
and the largest is
x
=
.
Note that the argument of a trig functions is measured in ra
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 Fall '10
 Drury
 Trigonometry, Sin, Expression, Order theory

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