CHAPTER 0 PRELIMINARIES
SECTION 0.6 Operations on Functions
Problem Set 0.6, Number 22 – 42.
- Sketch the graph of G(t) = t –〚t〛.
- State whether each of the following is an odd function, an even function, or neither. Prove your statements.
- Let F be any function whose domain contains –x whenever it contains x. Prove each of the following.
- Is every polynomial of even degree an even function? Is every polynomial of odd degree an odd function? Explain.
- Classify each of the following as a PF (polynomial function), RF (rational function but not a polynomial function), or neither.
- The relationship between the unit price P (in cents) for a certain product and the demand D (in thousans of units) appears to satisfy
- After being in business for t years, a manufacturer of cars is making 120 + 2t + 3t2 units per year. The sales price in dollars per unit has risen according to the formula 6000 + 700t. Write a formula for the manufacturer's yearly revenue R(t) after t years.
- Starting at noon, airplane A flies due north at 400 miles per hour. Starting 1 hour later, airplane B flies due east at 300 miles per hour. Neglecting the curvature of the Earth and assuming that they fly at the same altitude, find a formula for D(t), the distance between the two airplanes t hours after noon. Hint: There will be two formulas for D(t), one if 0 < t < 1 and the other if t ≥ 1.
- Fin the distance between the airplanes of Problem 29 at 2:30 p.m.
- Let f(x) = [ax + b] / [cx – a]. Show that f(f(x)) = x, provided a2 + bc ≠ 0 and x ≠ a/c.
- Let f(x) = [x – 3] / [x + 1]. Show that f(f(f(x))) = x, provided x ≠ ±1.
- Let f(x) = [x] / [x – 1]. Find and simplify each value.
- Let f(x) = [x] / [√(x) – 1]. Find and simplify.
- Prove that the operation of composition of functions is associative; that is, f1 ◦ (f2 ◦ f3) = (f1 ◦ f2) ◦ f3.
- Let f1(x) = x, f2(x) = 1/x, f3(x) = 1 – x, f4(x) = 1 / (1 – x), f5(x) = (x – 1) / x, and f6(x) = x / (x – 1) . Note that f3(f4(x)) = f3(1 / (1 – x)) = 1 – 1/(1 – x) = x / (x – 1) = f6(x) that is, f3 ◦ f4 = f4. In fact, the composition of any two of these functions is another one in the list. Fill in the composition table in Figure 11.
- Let f(x) = x2 – 3x. Using the same axes, draw the graphs of y = f(x), y = f(x – 0.5) – 0.6, and y = f(1.5x), all on the domain [–2, 5].
- Let f(x) = |x3|. Using the same axes, draw the graphs of y = f(x), y = f(3x), and y = f(3(x – 0.8)), all on the domain [–3, 3].
- Let f(x) = 2√(x) – 2x + 0.25x2. Using the same axes, draw the graphs of y = f(x), y = f(1.5x), and y = f(x – 1) + 0.5, all on the domain [0, 5].
- Let f(x) = 1/(x2 + 1). Using the same axes, draw the graphs of y = f(x), y = f(2x), and y = f(x – 2) + 0.6, all on the domain [–4, 4].
- Your computer algebra system (CAS) may allow the use of parameters in defining functions. In each case, draw the graph of y = f(x) for the specified values of the parameter k, using the same axes and –5 ≤ x ≤ 5.
- Using the same axes, draw the graph of f(x) = |k(x – c)|n for the following of parameters.
💬 SOLUTION:
(a)
|
The sum of two even functions
|
(b)
|
The sum of two odd functions
|
(c)
|
The product of two even functions
|
(d)
|
The product of two odd functions
|
(e)
|
The product of an even function and an odd
function
|
💬 SOLUTION:
(a)
|
Even;
|
|
(f + g)(–x) = f(–x)
+ g(–x) = f(x) + g(x)
|
|
= (f + g)(x) if f and g
are both even functions.
|
(b)
|
Odd;
|
|
(f + g)(–x) = f(–x)
+ g(–x) = –f(x) – g(x)
|
|
= –(f + g)(x) if f
and g are both odd functions.
|
(c)
|
Even;
|
|
(f ∙ g)(–x) = [f(–x)][g(–x)]
|
|
= [f(x)][g(x)]
= (f ∙ g)(x)
|
|
if f and g are both even
functions.
|
(d)
|
Even;
|
|
(f ∙ g)(–x) = [f(–x)][g(–x)]
|
|
= [–f(x)][–g(x)]
= [f(x)][g(x)]
|
|
= (f ∙ g)(x)
|
|
if f and g are both odd
functions.
|
(e)
|
Odd;
|
|
(f ∙ g)(–x) = [f(–x)][g(–x)]
|
|
= [f(x)][–g(x)]
= –[f(x)][g(x)]
|
|
= –(f ∙ g)(x)
|
|
if f is an even function and g
is an odd function.
|
(a)
|
F(x) – F(–x) is an odd function.
|
(b)
|
F(x) + F(–x) is an odd function.
|
(c)
|
F can always be expressed as the sum of an odd and an even function.
|
💬 SOLUTION:
(a)
|
F(x) – F(–x) is odd because
|
|
F(–x) – F(x) = –[F(x) – F(–x)]
|
(b)
|
F(x) + F(–x) is even because
|
|
F(–x) + F(–(–x)) = F(–x) + F(x)]
|
|
= F(x) + F(–x)
|
(c)
|
[F(x) – F(–x)]
/ 2 is odd an [F(x) + F(–x)] / 2 is even.
|
|
[[F(x) – F(–x)]
/ 2 ] + [[F(x) + F(–x)] / 2]
|
|
= [2F(x)] / 2
|
|
= F(x)
|
💬 SOLUTION:
Not every polynomial of even degree is an even function. For example f(x) = x2 + x is neither even nor odd. Not every polynomial of odd degree is an odd function. For example g(x) = x3 + x2 is neither even nor odd.
(a)
|
f(x) = 3x1/2 + 1
|
(b)
|
f(x) = 3x2 + 2x–1
|
(c)
|
f(x) = 1 / (x + 1)
|
(d)
|
f(x) = 3
|
(e)
|
f(x) = πx3 – 3π
|
(f)
|
f(x) = (x + 1) / [√(x + 3)]
|
💬 SOLUTION:
(a)
|
Neither
|
(b)
|
PF
|
(c)
|
RF
|
(d)
|
PF
|
(e)
|
RF
|
(f)
|
Neither
|
P = √(29 – 3D + D2)
On the other hand, the demand has risen over the t tears since 1970 according to D = 2 + √(t).
(a)
|
Express P as a function of t.
|
(b)
|
Evaluate P when t = 15.
|
💬 SOLUTION:
(a)
|
P = √[29 – 3(2 + √(t)) + (2 + √(t))2]
|
|
P = √[(t) + √(t) + 27]
|
(b)
|
When t = 15, P = √[(15) + √(15)
+ 27] ≈ 6.773
|
💬 SOLUTION:
P(t) = (120 + 2t + 3t2)(6000 + 700t)
|
= 2100t3 + 19, 400t2
+ 96, 000t + 720, 000
|
BACA JUGA:
|
|
💬 SOLUTION:
D(t) =
|
{
|
400t
|
if 0 < t < 1
|
√((400t)2 + [300(t
– 1]2)
|
If t ≥ 1
|
||
D(t) =
|
{
|
400t
|
If 0 < t < 1
|
√(250, 00t2 – 180, 000t
+ 90, 000)
|
If t ≥ 1
|
💬 SOLUTION:
D(2.5) ≈ 1097 mi
💬 SOLUTION:
f(f(x))
|
=
|
f(
|
ax + b
|
)
|
cx – a
|
|
=
|
a(
|
ax + b
|
) + b
|
cx – a
|
||||
c(
|
ax + b
|
) – a
|
||
cx – a
|
If a2 + bc = 0, f(f(x))
is undefined, while if x = a/c, f(x) is
undefined.
|
💬 SOLUTION:
f(f(f(x)))
|
=
|
f(f(
|
x – 3
|
))
|
x + 1
|
|
=
|
f(
|
x – 3
|
– 3
|
)
|
x + 1
|
|||||
x – 3
|
+ 1
|
||||
x + 1
|
|
=
|
f(
|
x – 3 – 3x – 3
|
)
|
x – 3 + x + 1
|
|
=
|
f(
|
–2x – 6
|
)
|
2x – 2
|
|
=
|
f(
|
–x – 3
|
)
|
x – 1
|
|
=
|
–x – 3
|
– 3
|
x – 1
|
|||
–x – 3
|
+ 1
|
||
x – 1
|
|
=
|
–x – 3 – 3x
+ 3
|
–x – 3 + x
– 1
|
|
=
|
–4x
|
–4
|
|
=
|
x
|
If x = –1, f(x) is
undefined, while if x = 1, f(f(x)) is undefined.
|
(a)
|
f(1/x)
|
(b)
|
f(f(x))
|
(c)
|
f(1/f(x))
|
💬 SOLUTION:
(a)
|
f(
|
1
|
)
|
=
|
1/x
|
=
|
1
|
x
|
(1/x) – 1
|
1 – x
|
(b)
|
f(f(x))
|
=
|
f(
|
x
|
)
|
x – 1
|
|
|
=
|
x
|
|
x – 1
|
||||
x
|
– 1
|
|||
x – 1
|
|
|
=
|
x
|
x – x + 1
|
|
|
=
|
x
|
(c)
|
f(
|
1
|
)
|
=
|
f(
|
x
|
)
|
f(x)
|
x – 1
|
|
|
=
|
x – 1
|
|
x
|
||||
x – 1
|
– 1
|
|||
x
|
|
|
=
|
x – 1
|
x – 1 – x
|
|
|
=
|
1 – x
|
(a)
|
f(1/x)
|
(b)
|
f(f(x))
|
💬 SOLUTION:
(a)
|
f(
|
1
|
)
|
=
|
1/x
|
=
|
1
|
x
|
√(1/x) – 1
|
√(x) – x
|
(b)
|
f(f(x))
|
=
|
f(x/(√(x) – 1))
|
|
|
=
|
x/(√(x) – 1)
|
||
√(
|
x
|
) – 1
|
|||
|
√(x) – 1
|
|
|
=
|
x
|
√[x(√(x)
– 1)] + 1 – √(x)
|
💬 SOLUTION:
(f1
◦ (f2 ◦ f3))(x)
|
=
|
f1 ◦
((f2 ◦ f3)(x))
|
|
=
|
f1 (f2
(f3(x)))
|
((f1
◦ f2) ◦ f3)(x)
|
=
|
(f1 ◦ f2)
(f3(x))
|
|
=
|
f1 (f2
(f3(x)))
|
|
=
|
(f1 ◦ (f2
◦ f3))(x)
|
BACA JUGA:
|
|
Figure 11
Then use this table to find each of the following. From Problem 35, you know that the associative law holds.
(a)
|
f3 ◦
f3 ◦ f3 ◦ f3 ◦ f3
|
(b)
|
f1 ◦
f2 ◦ f3 ◦ f4 ◦ f5
◦ f6
|
(c)
|
F if F ◦ f6 = f1
|
(d)
|
G if G ◦ f3 ◦ f6 = f1
|
(e)
|
G if f2 ◦ f5 ◦ H = f5
|
💬 SOLUTION:
f1(f1(x))
|
=
|
x
|
;
|
f1(f2(x))
|
=
|
1
|
;
|
x
|
f1(f3(x))
|
=
|
1 – x
|
;
|
f1(f4(x))
|
=
|
1
|
;
|
1 – x
|
f1(f5(x))
|
=
|
x – 1
|
;
|
x
|
f1(f6(x))
|
=
|
x
|
;
|
x – 1
|
f2(f1(x))
|
=
|
1
|
;
|
x
|
f2(f2(x))
|
=
|
1
|
=
|
x
|
;
|
1/x
|
f2(f3(x))
|
=
|
1
|
;
|
1 – x
|
f2(f4(x))
|
=
|
1
|
=
|
1 – x
|
;
|
1/(1 – x)
|
f2(f5(x))
|
=
|
1
|
=
|
x
|
;
|
(1 – x)/x
|
x – 1
|
f2(f6(x))
|
=
|
1
|
=
|
x – 1
|
;
|
x/(x – 1)
|
x
|
f3(f1(x))
|
=
|
1 – x
|
;
|
f3(f2(x))
|
=
|
1 –
|
1
|
=
|
x – 1
|
;
|
x
|
x
|
f3(f3(x))
|
=
|
1 – (1 – x)
|
=
|
x
|
;
|
f3(f4(x))
|
=
|
1 –
|
1
|
=
|
x
|
;
|
1 – x
|
x – 1
|
f3(f5(x))
|
=
|
1 –
|
x – 1
|
=
|
1
|
;
|
x
|
x
|
f3(f6(x))
|
=
|
1 –
|
x
|
=
|
1
|
;
|
x – 1
|
1 – x
|
f4(f1(x))
|
=
|
1
|
;
|
1 – x
|
f4(f2(x))
|
=
|
1
|
=
|
x
|
;
|
1 – (1/x)
|
x – 1
|
f4(f3(x))
|
=
|
1
|
=
|
1
|
;
|
1 – (1 – x)
|
x
|
f4(f4(x))
|
=
|
1
|
=
|
1 – x
|
=
|
x – 1
|
;
|
1 – [1/(1 – x)]
|
1 – x – 1
|
x
|
f4(f5(x))
|
=
|
1
|
=
|
x
|
=
|
x
|
;
|
1 – [(x – 1)/x]
|
x – (x – 1)
|
f4(f6(x))
|
=
|
1
|
=
|
x – 1
|
=
|
1 – x
|
;
|
1 – [x/(x
– 1)]
|
x – 1 – x
|
f5(f1(x))
|
=
|
x – 1
|
;
|
x
|
f5(f2(x))
|
=
|
(1/x) – 1
|
=
|
1 – x
|
;
|
1/x
|
f5(f3(x))
|
=
|
1 – x – 1
|
=
|
x
|
;
|
1 – x
|
x – 1
|
f5(f4(x))
|
=
|
[1/(1 – x)] –
1
|
=
|
1 – (1 – x)
|
=
|
x
|
;
|
1/(1 – x)
|
1
|
f5(f5(x))
|
=
|
[(x – 1)/x]
– 1
|
=
|
x – 1 – x
|
=
|
1
|
;
|
(x – 1)/x
|
x – 1
|
1 – x
|
f5(f6(x))
|
=
|
[x/(x
– 1)] – 1
|
=
|
x – (x – 1)
|
=
|
1
|
;
|
x/(x – 1)
|
x
|
x
|
f6(f1(x))
|
=
|
x
|
;
|
x – 1
|
f6(f2(x))
|
=
|
1/x
|
=
|
1
|
;
|
(1/x) – 1
|
1 – x
|
f6(f3(x))
|
=
|
1 – x
|
=
|
x – 1
|
;
|
1 – x – 1
|
x
|
f6(f4(x))
|
=
|
[1/(1 – x)]
|
=
|
1
|
=
|
1
|
;
|
[1/(1 – x)]
– 1
|
1 – (1 – x)
|
x
|
f6(f5(x))
|
=
|
[(x – 1)/x]
|
=
|
x – 1
|
=
|
1 – x
|
;
|
[(x – 1)/x]
– 1
|
x – 1 – x
|
f6(f6(x))
|
=
|
x/(x – 1)
|
=
|
x
|
=
|
x
|
[x/(x
– 1)] – 1
|
x – (x – 1)
|
◦
|
f1
|
f2
|
f3
|
f4
|
f5
|
f6
|
f1
|
f1
|
f2
|
f3
|
f4
|
f5
|
f6
|
f2
|
f2
|
f1
|
f4
|
f3
|
f6
|
f5
|
f3
|
f3
|
f5
|
f1
|
f6
|
f2
|
f4
|
f4
|
f4
|
f6
|
f2
|
f5
|
f1
|
f3
|
f5
|
f5
|
f3
|
f6
|
f1
|
f4
|
f2
|
f6
|
f6
|
f4
|
f5
|
f2
|
f3
|
f1
|
(a)
|
f3 ◦
f3 ◦ f3 ◦ f3 ◦ f3
|
|
= (((( f3 ◦ f3
) ◦ f3 ) ◦ f3 ) ◦ f3 )
|
|
= ((( f1 ◦ f3
) ◦ f3 ) ◦ f3 )
|
|
= (( f3 ◦ f3
) ◦ f3 )
|
|
= f1 ◦ f3
|
|
= f3
|
(b)
|
f1 ◦
f2 ◦ f3 ◦ f4 ◦ f5
◦ f6
|
|
= ((((( f1 ◦ f2
) ◦ f3 ) ◦ f4 ) ◦ f5 ) ◦
f6 )
|
|
= (((( f2 ◦ f3
) ◦ f4 ) ◦ f5 ) ◦ f6 )
|
|
= ( f4 ◦ f4
) ◦ ( f5 ◦ f6 )
|
|
= f5 ◦ f2
|
|
= f3
|
(c)
|
If F ◦ f6 = f1,
then F = f6.
|
(d)
|
If G ◦ f3 ◦ f6
= f1, then G ◦ f4 = f1
so
|
|
G = f5.
|
(e)
|
If f2 ◦ f5
◦ H = f5, then f6 ◦ H = f5
so
|
|
H = f3.
|
Use a computer or a graphing calculator in Problems 37 – 40
💬 SOLUTION:
💬 SOLUTION:
💬 SOLUTION:
💬 SOLUTION:
(a)
|
f(x) = |kx|0.7 for k = 1, 2, 0.5, and
0.2.
|
(b)
|
f(x) = |x – k|0.7 for k = 0, 2, –0.5,
and –3.
|
(c)
|
f(x) = |x|k for k = 0.4, 0.7, 1,
and 1.7.
|
💬 SOLUTION:
(a)
|
c = –1, k = 1.4, n = 0.7
|
(b)
|
c = 2, k = 1.4, n = 1
|
(c)
|
c = 0, k = 0.9, n = 0.6
|
💬 SOLUTION:
BACA JUGA:
|
|
Demikian soal serta penjelasan untuk Pembahasan Soal Buku Calculus 9th Purcell Chapter 0 - 0.6 Number 22 – 42. Silahkan untuk berkunjung kembali dikarenakan akan selalu ada update terbaru 😊😄🙏. Silahkan juga untuk memilih dan mendiskusikan di tempat postingan ini di kolom komentar ya supaya semakin bagus diskusi pada setiap postingan. Diperbolehkan request di kolom komentar pada postingan ini tentang rangkuman atau catatan atau soal dan yang lain atau bagian hal yang lainnya, yang sekiranya belum ada di website ini. Terima kasih banyak sebelumnya 👍. Semoga bermanfaat dan berkah untuk kita semua. Amiiinnn 👐👐👐
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