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Larson et al - Elementary Linear Algebra 6/e (Homework)

James Finch

Math - College, section 1, Fall 2010

Instructor: Dr. Friendly

Current Score: 4/47

Due: Friday, September 10, 2010 22:00 EDT

About this Assignment

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Question
Points
1 2 3 4 5 6 7 8 9 10 11
2/3 0/2 0/1 2 0/3 0/2 0/3 0/3 0/11 0/15 0/2
Total
4/47

Description

Here are some textbook questions from Elementary Linear Algebra 6/e by Ron Larson, Bruce H. Edwards, and David C. Falvo published by Brooks/Cole. Click here for a list of all of the questions coded in WebAssign.


Instructions

This demo assignment allows many submissions and allows you to try another version of the same question for practice.



1. 2/3 points All Submissions Notes Question: LarLinAlg6 1.1.017.
Question part
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0/1 1 1
3/50 1/50 1/50
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2/3
 
Graph the system of equations as a pair of lines in the xy-plane.
2x + y = 4
x – y = 2

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Solve the system and interpret your answer. (If there is no solution, enter NO SOLUTION. If the system has an infinite number of solutions set y = t and solve for x in terms of t.)
x =
Enter a mathematical expression.
Your answer is correct.
y =
Enter a mathematical expression.
Your answer is correct.

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2. –/2 points Notes Question: LarLinAlg6 1.1.037.
Question part
Points
Submissions
1 2
0/1 0/1
0/50 0/50
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0/2
 
Solve the system of linear equations. (If there is no solution, enter NO SOLUTION.)
x1 – x2 = 0
2x1 – 4x2 = -6
x1 =
Enter an exact number as an integer, fraction, or decimal.
x2 =
Enter an exact number as an integer, fraction, or decimal.

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3. –/1 points Notes Question: LarLinAlg6 1.1.085.
Question part
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0/1
 
Determine the values of k such that the system of linear equations does not have a unique solution. (Enter your answers as a comma-separated list.)
x + y + kz = 4
x + ky + z = 6
kx + y + z = 8
k =

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4. 2/2 points All Submissions Notes Question: LarLinAlg6 1.2.001.
Question part
Points
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1 2
1 1
1/50 1/50
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2/2
 
Determine the size of the matrix.
 
 
19–9–18
 
 
Enter an exact number.
Your answer is correct.cross
Enter an exact number.
Your answer is correct.

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5. –/3 points Notes Question: LarLinAlg6 1.2.029.
Question part
Points
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1 2 3
0/1 0/1 0/1
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0/3
 
Solve the system using either Gaussian elimination with back-substitution or Gauss-Jordan elimination.
7x1 + 2x2 + 4x3 = 2
3x1 + x2 + 2x3 = 1
–3x1 – x2 – x3 = –2
x1 =
Enter an exact number.
x2 =
Enter an exact number.
x3 =
Enter an exact number.

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6. –/2 points Notes Question: LarLinAlg6 1.3.003.
Question part
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1 2
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0/2
 
Consider the following points.
(0, 5), (6, -7), (1, 3)
(a) Determine the polynomial function whose graph passes through the given points.
p(x) =

(b) Sketch the graph of the polynomial function, showing the given points.

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7. –/3 points Notes Question: LarLinAlg6 1.3.013.SBS.
Question part
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1 2 3
0/1 0/1 0/1
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0/3
 
The U.S. census lists the population of the United States as 227 million in 1980, 249 million in 1990, and 281 million in 2000. Fit a second-degree polynomial passing through these three points and use it to predict the population in 2019 and in 2025.† (Round your answers to the nearest million.)
STEP 1: Let x represent the year. Write a polynomial in t where t = x – 1990.
p(t) =

STEP 2: Substitute the appropriate values of t for the predictions. (Round your answers to the nearest integer.)
2019 prediction
Enter a number.
 million
2025 prediction
Enter a number.
 million

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8. –/3 points Notes Question: LarLinAlg6 1.3.025.
Question part
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1 2 3
0/1 0/1 0/1
0/50 0/50 0/50
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0/3
 
Determine the currents I1, I2, and I3 for the electrical network shown in the figure below. (Let V1 = 9 and V2 = 12.)
I1 =
Enter an exact number.
I2 =
Enter an exact number.
I3 =
Enter an exact number.

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9. –/11 points Notes Question: LarLinAlg6 2.1.009.SBS.
Question part
Points
Submissions
1 2 3 4 5 6 7 8 9 10 11
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50
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0/11
 
Solve for x, y, and z in the matrix equation.
12
 
 
xy
z–1
 
 
   =   6
 
 
yz
–x1
 
 
   +   6
 
 
4x
5–x
 
 
STEP 1: Simplify the right side of the equation.
12
 
 
xy
z–1
 
 
   =  
 
 
 
 

STEP 2: Set corresponding entries equal to each other to obtain four equations.
12x =
12y =
12z =
−12 =

STEP 3: Solve for x, y, and z.
x =
Enter an exact number as an integer, fraction, or decimal.
y =
Enter an exact number as an integer, fraction, or decimal.
z =
Enter an exact number as an integer, fraction, or decimal.

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10. –/15 points Notes Question: LarLinAlg6 2.1.013.
Question part
Points
Submissions
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50
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0/15
 
Consider the matrices shown below.
A =
 
 
–78
–63
2–1
 
 
    B =
 
 
41–3
2–9–10
86–1
 
 
Find the following (if they are defined). (If a product is undefined, enter UNDEFINED in each answer blank for that product.)
(a)    AB
 
 
Enter a number.
Enter a number.
Enter a number.
Enter a number.
Enter a number.
Enter a number.
Enter a number.
Enter a number.
Enter a number.
 
 

(b)    BA
 
 
Enter an exact number.
Enter an exact number.
Enter an exact number.
Enter an exact number.
Enter an exact number.
Enter an exact number.
 
 

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11. 0/2 points All Submissions Notes Question: LarLinAlg6 2.1.021.
Question part
Points
Submissions
1 2
0/1 0/1
1/50 1/50
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0/2
 
Let A, B, C, D, and E be matrices with the provided orders.
A: 3 cross 3      B: 4 cross 4      C: 2 cross 4      D: 2 cross 4      E: 3 cross 4
If defined, determine the size of the matrix A + B. (If an answer is undefined, enter UNDEFINED.)
Enter a number.
Your answer is incorrect. cross
Enter a number.
Your answer is incorrect.

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