Applied Finite Mathematics by Rupinder Sekhon, UniqU, LLC - HTML preview

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Chapter 4Matrices: Homework

INTRODUCTION TO MATRICES

A vendor sells hot dogs and corn dogs at three different locations. His total sales (in hundreds) for January and February from the three locations are given in the table below.

Table 4.1.
 
JanuaryFebruary
Hot DogsCorn DogsHot DogsCorn Dogs
Place I10887
Place II8667
Place III6465

Represent these tables as 3×2 matrices J and F, and answer Exercise 1., Exercise 2., Exercise 3., and Exercise 4.. problems 1 - 4.

Determine total sales for the two months, that is, find J+F.

(4.1)
_autogen-svg2png-0005.png
Exercise 2.

Find the difference in sales, JF.

If hot dogs sell for $3 and corn dogs for $2, find the revenue from the sale of hot dogs and corn dogs. Hint: Let P be a 2×1 matrix. Find (J+F)P.

(4.2)
_autogen-svg2png-0010.png
Exercise 4.

If March sales will be up from February by 10%, 15%, and 20% at Place I, Place II, and Place III, respectively, find the expected number of hot dogs, and corn dogs to be sold in March. Hint: Let R be a 1×3 matrix with entries 1.10, 1.15, and 1.20. Find _autogen-svg2png-0013.png.

Determine the sums and products in the next 5 problems. Given the matrices A, B, C, and D as follows:

_autogen-svg2png-0018.png _autogen-svg2png-0019.png _autogen-svg2png-0020.png _autogen-svg2png-0021.png

(4.3)3A−2B
(4.4)
_autogen-svg2png-0023.png
Exercise 6.
(4.5)
_autogen-svg2png-0024.png
(4.6)A2
(4.7)
_autogen-svg2png-0026.png
Exercise 8.
(4.8)
_autogen-svg2png-0027.png
(4.9)
_autogen-svg2png-0028.png
(4.10)
_autogen-svg2png-0029.png
Exercise 10.
(4.11)A2B

Let _autogen-svg2png-0031.png and _autogen-svg2png-0032.png, find _autogen-svg2png-0033.png.

(4.12)
_autogen-svg2png-0034.png
Exercise 12.

Let _autogen-svg2png-0035.png , find _autogen-svg2png-0036.png.

Express the following systems as _autogen-svg2png-0037.png, where A, X, and B are matrices.

(4.13)4x−5y=6
(4.14)5x−6y=7
(4.15)
_autogen-svg2png-0043.png
Exercise 14.
(4.16)x−2y+2z=3
(4.17)x−3y+4z=7
(4.18)x−2y−3z=−12
(4.19)2x+3z=17
(4.20)3x−2y=10
(4.21)5y+2z=11
(4.22)
_autogen-svg2png-0050.png
Exercise 16.
(4.23)
_autogen-svg2png-0051.png

SYSTEMS OF LINEAR EQUATIONS

Solve the following by the Gauss-Jordan Method. Show all work.

(4.24)x+3y=1
(4.25)2x−5y=13
(4,-1)
Exercise 18.
(4.26)xyz=−1
(4.27)x−3y+2z=7
(4.28)2x−y+z=3
(4.29)x+2y+3z=9
(4.30)3x+4y+z=5
(4.31)2x−y+2z=11
(2, -1, 3)
Exercise 20.
(4.32)x+2y=0
(4.33)y+z=3
(4.34)x+3z=14

Two apples and four bananas cost $2.00 and three apples and five bananas cost $2.70. Find the price of each.

(0.4, 0.3)
Exercise 22.

A bowl of corn flakes, a cup of milk, and an egg provide 16 grams of protein. A cup of milk and two eggs provide 21 grams of protein, and two bowls of corn flakes with two cups of milk provide 16 grams of protein. How much protein is provided by one unit of each of these three foods.

(4.35)x+2y=10
(4.36)y+z=5
(4.37)z+w=3
(4.38)x+w=5
(4, 3, 2, 1)
Exercise 24.
(4.39)x+w=6
(4.40)2x+y+w=16
(4.41)x−2z=0
(4.42)z+w=5

SYSTEMS OF LINEAR EQUATIONS – SPECIAL CASES

Solve the following inconsistent or dependent systems by using the Gauss-Jordan method.

(4.43)2x+6y=8
(4.44)x+3y=4
(4.45)(4−3t,t)
Exercise 26.

The sum of the digits of a two digit number is 9. The sum of the number and the number obtained by interchanging the digits is 99. Find the number.

(4.46)2x−y=10
(4.47)−4x+2y=15
Inconsistent system, no solution
Exercise 28.
(4.48)x+y+z=6
(4.49)3x+2y+z=14
(4.50)4x+3y+2z=20
(4.51)x+2y−4z=1
(4.52)2x−3y+8z=9
(3−4/7t,−1+16/7t,t)
Exercise 30.

Jessica has a collection of 15 coins consisting of nickels, dimes and quarters. If the total worth of the coins is $1.80, how many are there of each? Find all three solutions.

The latest reports indicate that there are altogether 20,000 American, French, and Russian troops in Bosnia. The sum of the number of Russian troops and twice the American troops equals 10,000. Furthermore, the Americans have 5,000 more troops than the French. Are these reports consistent?

No, they are not consistent.
Exercise 32.