Name:
Math 5: Test 1
February 20, 2012
Please write neatly and clearly. Problems 14 are multiple choice, and you do not need
to show your work. Problems 59 are partial credit; you should show your work and identify
your ﬁnal answer.
You may use a calculator. However, no cell phones or books may be used.
Question:
1
2
3
4
5
6
7
8
9
Total
Points:
5
10
20
5
10
20
10
10
10
100
Score:
1. (5 points) I am 30 years older than my daughter. In 12 years from now, I will be 3 times as old as she is.
If we let
x
denote my age and
y
denote my daughter’s age, which of the following systems of equations
would you solve to determine how old my daughter and I are?
A.
(
x
+
y
= 30
3
x
+ 12 =
y
+ 12
B.
(
y
=
x
+ 30
3(
x
+ 12) =
y
+ 12
C.
(
x
=
y
+ 30
x
+ 12 = 3(
y
+ 12)
D.
(
x
=
y
+ 30
x

12 = 3(
y

12)
2. (10 points) Given the matrices
A
=
1 0 2
0 1 3
0 0 1
,
B
=
±
3 1 0
0 3 1
²
,
C
=
1

1
0
2

2
0
compute the following.
(a)
CB
+ 3
A
= ? A. Undeﬁned
B.
±
3

1

2
6
²
C.
1 0 0
0 1 0
0 0 1
D.
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 Spring '13
 Dr. Corbett Redden
 Math, Gaussian Elimination, $100, $10,000, Row echelon form, $2,000

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