12-240/Classnotes for Thursday September 27: Difference between revisions

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'''Vector Spaces'''
In this course, we will be focusing on both a practical side and a theoretical side.


== Vector space axioms ==
== Vector space axioms ==

''(Quick recap)''
''(Quick recap)''

VS1. x + y = y + x
VS1. x + y = y + x

VS2. (x + y) + z = x + (y + z)
VS2. (x + y) + z = x + (y + z)

VS3. 0 vector
VS3. 0 vector

VS4. + inverse -> -
VS4. + inverse -> -

VS5. 1x = x
VS5. 1x = x

VS6. a(bx) = (ab)x
VS6. a(bx) = (ab)x

VS7. a(x + y) = ax + ay
VS7. a(x + y) = ax + ay

VS8. (a+b)x = ax + bx
VS8. (a+b)x = ax + bx

== Theorems ==

1.a x + z = y + z => x = y

1.b ax = ay, a != 0, => x = y

1.c ax = bx, x != 0, => a = b



2. 0 is unique.


3. Additive inverse is unique.


4. 0_F * x = 0_V


5. a * 0_V = 0_V


6. (-a) x = -(ax) = a(-x)


7. cx = 0 <=> c = 0 or x = 0_V

Revision as of 20:26, 27 September 2012

Vector Spaces

Vector space axioms

(Quick recap)

VS1. x + y = y + x

VS2. (x + y) + z = x + (y + z)

VS3. 0 vector

VS4. + inverse -> -

VS5. 1x = x

VS6. a(bx) = (ab)x

VS7. a(x + y) = ax + ay

VS8. (a+b)x = ax + bx

Theorems

1.a x + z = y + z => x = y

1.b ax = ay, a != 0, => x = y

1.c ax = bx, x != 0, => a = b


2. 0 is unique.


3. Additive inverse is unique.


4. 0_F * x = 0_V


5. a * 0_V = 0_V


6. (-a) x = -(ax) = a(-x)


7. cx = 0 <=> c = 0 or x = 0_V