Math 43, Fall 2007
B. Dodson
Hour Exams:
Exam 1 will be on Friday, October 12;
and Exam 2 will be on Wednesday, November 14,
at our regularly scheduled class time, 11:10-12:00.
Week 2:
Finish suggested homework 1, consisting of the
problems on graded hw 1 plus
1.1 - 5d, 7, 10, 11, 19, 21; 1.2 - 2, 9, 30.
Graded Homework 2:
1.2 - 34 and 1.3 - 4,
due Mon. Sept 10
Suggested Homework 2:
problems from graded
Homework 2 plus 1.2 - 22, 23, 35, 36; 1.3 - 6,
due (but not collected) Wed. Sept. 12.
Second week.
4. Problem 1.2.9, Section 1.2, pg. 26:
Find
||
±u
||
and a unit vector in the direction of
±u
when
±u
= [1
,
2
,
3]
.
Solution:
For
±v
we have
||
±v
||
=
√
±v
◦
±v,
so for
±v
= [
v
1
, v
2
, v
3
]
,
||
±v
||
=
p
v
2
1
+
v
2
1
+
v
2
1
.
so
||
±u
||
=
√
±u
◦
±u
=
√
1 + 4 + 9 =
√
14
.
Then the unit vector in the direction of
±u
is
1
√
14
[1
,
2
,
3] = [
1
√
14
,
2
√
14
,
3
√
14
]
.