150603_uwin-me02-s52
DESCRIPTION
150603_UWIN-ME02-s52TRANSCRIPT
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Bachelor in Economics (S.E): Manajemen
Course : Matematika Ekonomi (1506ME02)
online.uwin.ac.id
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Session Topic : Jenis-jenis Fungsi Linear
Course: Matematika Ekonomi
By Handri Santoso, Ph.D
UWIN eLearning Program
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Content
Part 1 Pengertian & Jenis-jenis Fungsi
Part 2 Pengertian Fungsi Linier
Part 3 Gradient
Part 4 Applications
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Part1: Pengertian & Jenis-jenis Fungsi
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Fungsi: Definisi
Fungsi
Defn:
Suatu bentuk hubungan matematis yang menyatakanhubungan ketergantungan (hub. fungsional)
.antara suatu variabel dengan variabel lain.
y = b + mx
Dependent
VariableKonstanta
Koefisien
Var. x
Independent
Variable
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Fungsi: Jenis
Jenis-jenis Fungsi
Fungsi
F.PangkatF. Polinom
F. Linier
F. Kuadrat
F. Kubik
F. Bikuadrat
Fungsi rasionalFungsi
irrasional
Fungsi non-aljabar
(transenden)
Fungsi aljabar
F. Eksponensial
F. Logaritmik
F. Trigonometrik
F. Hiperbolik
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Fungsi: Jenis (lanjut)
Fungsi,
1. Polinom
Defn: Fungsi yang mengandung banyak suku (polinom) dalam variabel bebasnya.
y = a0 + a1x + a2x2 + . + anx
n
2. Linear
Defn: Fungsi polinom khusus yang pangkat tertinggi dari variabelnya adalah pangkatsatu (fungsi berderajat satu).
y = a0 + a1x a1 0
3. Kuadrat
Defn: Fungsi polinom yang pangkat tertinggi dari variabelnya adalah pangkat dua, sering juga disebut fungsi berderajat dua.
y = a0 + a1x + a2x2 a2 0
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Fungsi: Jenis (lanjut)
4. Berderajat
Defn: Fungsi yang pangkat tertinggi dari variabelnya adalah pangkat n (n = bilangan nyata).
y = a0 + a1x + a2x2 + . + an-1x
n-1 + anxn an 0
5. Pangkat
Defn: Fungsi yang variabel bebasnya berpangkat sebuah bilangan nyata bukan nol.
y = xn n = bilangan nyata bukan nol
6. Eksponensial
Defn: Fungsi yang variabel bebasnya merupakan pangkat dari suatu konstanta bukannol.
y = nx n > 0
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Fungsi: Jenis (lanjut)
7. Logaritmik
Defn: Fungsi balik (inverse) dari fungsi eksponensial, variabel bebasnya merupakanbilangan logaritmik.
y = nlog x
8. Trigonometrik dan fungsi hiperbolik
Defn: Fungsi yang variabel bebasnya merupakan bilangan-bilangan goneometrik.
Persamaan,
a. Trigonometrik y = sin x
b. Hiperbolik y = arc cos x
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Fungsi: Jenis (lanjut)
Berdasarkan letak ruas variabel-variabelnya: Fungsi eksplisitdan implisit
No Fungsi Eksplisit Implisit
1. Umum y = f(x) f(x,y) = 0
2. Linear y = a0+a1x a0+a1x-y = 0
3. Kuadrat y = a0+a1x+a2x2 a0+a1x+a2x
2-y = 0
4. Kubik y = a0+a1x +a2x2+a3x
3 a0+a1x +a2x2+a3x
3-y = 0
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Fungsi: Jenis (lanjut)
x
y
x
yLinear
y = a0 + a1x
a0
Kemiringan = a1
(a) (b)0 0
Kuadratik
y = a0 + a1x + a2x2
a0
(Kasus a2 < 0)
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Fungsi: Jenis (lanjut)
x
y
x
y
(c) (d)
0 0
Kubik
y = a0 + a1x + a2x2 + a3x
3
a0
Bujur sangkar
hiperbolik
y = a / x
(a > 0)
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Fungsi: Jenis (lanjut)
x
y
x
y
(e) (f)
0 0
Eksponen
y = bx
(b > 1)
Logaritma
y = logb x
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Fungsi: Penyimpangan Eksponen
xn = x x x x..x x
Aturan,
a. I : xm x xn = xm+n
Contoh : x3 x x4 = x7
b. II : xm / xn = xm-n
Contoh : x4 / x3 = x
c. III : x-n = 1/xn (x 0 )
d. IV : x0 = 1 (x 0)
e. V : x1/n =
f. VI : (xm)n = xmn
g. VII : xm x ym = (xy)m
n x
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Part2: Pengertian Fungsi Linier
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Fungsi Linier: Pengertian
Pengertian Fungsi Linier
Fungsi Linier
Defn: Fungsi polinom yang variabel bebasnya memiliki pangkat
paling tinggi satu.
Definisi:
y = b + mx
b = konstanta nilai positif, negatif atau nol
m = konstanta nilai positif, negatif atau nol
Contoh:
y = 4 + 2x
b = 4, m = 2
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Fungsi Linier: Gradient
Kemiringan (gradient) suatu garis
Fungsi polinom yang variabel bebasnya memiliki pangkat paling
tinggi satu.
Definisi:
y = b + mx
b = konstanta nilai positif, negatif atau nol
m = konstanta nilai positif, negatif atau nol
Contoh:
y = 4 + 2x
b = 4, m = 2
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Fungsi Linier: Gradient (lanjut)
Kemiringan (gradient) suatu
garis
Kemiringan atau gradient darisuatu garis lurus
biasanya dinyatakandengan m.
y = mx + b
Slope y-Intercept
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Fungsi Linier: Gradient (lanjut)
Kemiringan suatu garis (non-vertikal)
Defn:
Suatu unit bilangan yang naik (atau turun) vertikal untuk setiapbagian perubahan dari kiri ke kanan
seperti pada gambar dibawah:
Negative slope, line falls.Positive slope, line rises.
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Fungsi Linier: Gradient (lanjut)
Persamaan linier,
ditulis dalam bentuk y = mx + b , yang ditulis sebagai slope-intercept form.
Begitu kita telah menentukan kemiringan dan y-intercept darisuatu garis, maka
akan mudah untuk membuat grafik dari persamaan tersebut
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Fungsi Linier: Gradient (lanjut)
Contoh berikut adalah
persamaan garis vertical.
Garis vertikal mempunyai bentuk persamaan
x = a. Vertical line
Persamaan garis vertical,
tidak dapat dituliskan dalam bentuk y=mx+b
sebab
gradien dari garis lurus tidak didefinisikan
seperti pada gambar
Slope is undefined.
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Fungsi Linier: Penggambaran
Penggambaran Fungsi Linier
Untuk menggambarkan fungsi linier bisa dilakukan dengan 2 cara, yaitu,
1. membuat tabel dan
2. dengan menentukan titik potong dengan sumbu-x dan sumbu-y
Contoh untuk fungsi y= 2x + 4
Dengan menentukan titik potong terhadap sumbu-x dan sumbu-y
Pertama jika y = 0, didapat x=-2, maka didapat koordinat (-2,0).
Kedua jika x=0, didapat y= 4, maka didapat koordinat (0, 4)
x -2 -1 0 1 2 3
y 0 2 4 6 8 10
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Fungsi Linier: Menggambarkan Fungsi
Fungsi y = 2x + 4
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Fungsi Linier: Menggambarkan Fungsi (lanjut)
Latihan
Buatlah grafik dari fungsi berikut dengan metode diatas
1. y = 2x 4
2. y = x 5
3. y = 8 3x
4. y = 5x 7
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Part3: Gradient
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Gradient: Finding the Slope of a Line
Mencari Kemiringan Garis (Gradient)
Given an equation of a line,
you can find its slope by writing the equation in slope-intercept form. If you are not given an equation, you can still find the slope of a line.
For instance,
suppose you want to find the slope of the line passing through the points (x1, y1) and (x2, y2), as shown in Figure
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Gradient: Finding the Slope of a Line (cont.)
As you move from left to right along this line,
a change of (y2 y1) units in the vertical direction corresponds
to a change of (x2 x1) units in the horizontal direction.
y2 y1 = the change in y = rise
and
x2 x1 = the change in x = run
The ratio of (y2 y1) to (x2 x1) represents the slope of the line..
that passes through the points (x1, y1) and (x2, y2).
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Gradient: Finding the Slope of a Line (cont.)
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Gradient: Finding the Slope of a Line (cont.)
When this formula is used for slope,
the order of subtraction is important.
Given two points on a line, you are free to label either one of them as (x1, y1) and the other as (x2, y2).
However,
once you have done this, you must form the numerator and
denominator using the same order of subtraction.
IncorrectCorrectCorrect
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Gradient: Finding the Slope of a Line (cont.)
For instance,
the slope of the line passing through
the points (3, 4) and (5, 7) can be calculated as
or, reversing the subtraction order in both the numerator and denominator, as
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Example 2: Finding the Slope of a Line Through 2 Points
Find the slope of the line passing through each pair of
points.
a. (2, 0) and (3, 1)
b. (1, 2) and (2, 2)
c. (0, 4) and (1, 1)
d. (3, 4) and (3, 1)
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Example 2: Solution (a)
Letting (x1, y1) = (2, 0) and (x2, y2) = (3, 1), you obtain a slope
of
See Figure
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Example 2: Solution (b)
The slope of the line passing through (1, 2) and (2, 2) is
See Figure
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Example 2: Solution (c)
The slope of the line passing through (0, 4) and (1, 1) is
See Figure
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Example 2: Solution (d)
The slope of the line passing through (3, 4) and (3, 1) is
See Figure
Because division by 0 is undefined,
the slope is undefined and
the line is vertical.
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Dua Garis Lurus: Bentuk Hubungan
Hubungan 2 Garis Lurus
Dalam sistem sepasang sumbu silang, dua buah garis lurus mempunyai 4 macam kemungkinan
bentuk hubungan:
1. Berimpit,
2. Sejajar,
3. Berpotongan ,
4. dan Tegak Lurus.
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Dua Garis Lurus: Hubungan (lanjut)
Berimpit:
y1 = ny2
a1 = na2
b1 = nb2
Sejajar:
a1 a2
b1 = b2
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Dua Garis Lurus: Hubungan (lanjut)
Berpotongan:
b1 b2
Tegak Lurus:
b1 = - 1/b2
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Persamaan Linear: Pencarian Akar-akar
Pencarian Akar-akar Persamaan Linear
Pencarian besarnya variable bilangan dari beberapa
persamaan linear,
dengan kata lain penyelesaian persamaan- persamaanlinear secara serempak (simultaneously),
dapat dilakukan melalui 3 macam cara,1. Substitusi
2. Eliminasi
3. Determinan
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Persamaan Linear: Pencarian Akar-akar (lanjut)
1. Cara Substitusi
Contoh:
Carilah nilai variable- variable x dan y dari dua persamaan
berikut:
2x + 3y = 21 dan x + 4y = 23
untuk variabel x, diperoleh x = 23-4y
2x + 3y = 21
2(23 4y) + 3y = 21
46 8y + 3y = 21
46 5y = 21
25 = 5y, y = 5 x = ?
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Persamaan Linear: Pencarian Akar-akar (lanjut)
2. Cara Eliminasi
Dua persamaan dengan dua bilangan anu,
dapat diselesaikan dengan cara menghilangkan untuk sementara (mengeliminasi) salah satu dari bilangan anu yang ada,
sehingga dapat dihitung nilai dari bilangan anu yang lain.
5y 25,5y-
468y2x
213y2x
2
1
234yx
213y2x
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Persamaan Linear: Pencarian Akar-akar (lanjut)
3. Cara Determinan
Bisa digunakan untuk menyelesaikan persamaan yang jumlahnyabanyak.
Determinan secara umum dilambangkan dengan notasi
afhdbigecchdbfgaei
ihg
fed
cba
db-ae ed
ba
3 derajad determinan
2 derajad determinan
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Persamaan Linear: Pencarian Akar-akar (lanjut)
Ada 2 persamaan:
ax + by = c
dx + ey = f
Penyelesaian untuk x dan y dapat dilakukan:
dbae
dcaf
e d
b a
f d
c a
D
Dyy
dbae
fbce
e d
b a
e f
b c
D
Dxx
Determinan
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Persamaan Linear: Pencarian Akar-akar (lanjut)
Contoh
2x + 3y = 21
x + 4y = 23
Penyelesaian untuk x dan y dapat dilakukan:
55
3
21
25
4 1
3 2
23 1
21 2
D
Dyy
5
15
4 1
3 2
4 23
3
D
Dxx
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Part4: Applications
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Applications
Didalam kehidupan sehari-hari, kemiringan dari garis dapat di
artikan sebagai,
rasio atau rate (laju perubahan)
Jika sumbu-x dan sumbu-y mempunyai,
a. unit pengukuran yang sama maka gradient (m) tidak
mempunyai satuan sehingga disebut rasio.
b. satuan pengukuran yang berbeda maka gradient (m) disebut
rate atau laju perubahan
Applications: Rasio & Rate
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Example 1 Using Slope as a Ratio
The maximum recommended slope of a wheelchair ramp is
A business is,
installing a wheelchair ramp that rises 22 inches over a horizontal length of 24 feet.
Is the ramp steeper than recommended?(Source: Americans with Disabilities Act Handbook)
Applications: Contoh 1
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The horizontal length of the ramp is 24 feet or 12(24) = 288 inches, as
shown in Figure
So, the slope of the ramp is
Because 0.083, the slope of the ramp is not steeper than recommended.
Applications: Solution 1
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Example 2 Predicting Sales
The sales for Best Buy were approximately $35.9 billion in 2006
and $40.0 billion in 2007. Using only this information, write a
linear equation that gives the sales (in billions of dollars) in terms
of the year. Then predict the sales for 2010. (Source: Best Buy
Company, Inc.)
Applications: Contoh 2
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Applications: Solution 2
Let t = 6 represent 2006. Then the two given values are represented by the data points (6, 35.9)
and (7, 40.0).
The slope of the line through these points is
Using the point-slope form, you can find the equation that relates the
sales y and the year t to be
y 35.9 = 4.1(t 6) Write in point-slope form.
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Applications: Solution 2 (lanjut)
y = 4.1t + 11.3
According to this equation, the sales for 2010 will be
y = 4.1(10) + 11.3
= 41 + 11.3
= $52.3 billion. (See Figure)
Write in slope-intercept form.
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Course : Matematika Ekonomi (1506ME02)