vector spaces questions

sickplaya

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Jan 12, 2006
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i am a university student starting on a linear algebra course and i am struggling with some vector spaces questions. Help would be greatly appreciated and solutions written with full steps would be very much helpful. Thanks.

1. Let V denote the set of ordered pairs of real numbers. If (a1, a2) and (b1, b2) are elements of V and c ∈ R (all real numbers), define

(a1, a2) + (b1, b2) = (a1 + b1, a2b2), c(a1, a2)=(ca1, a2)

Is V a vector space with these operations? (check all 8 axioms)

2. Let V and W be vector spaces. Let Z = {(v,w)| v∈V, w∈W}. Prove Z is a vector space with the operations

(v1, w1) + (v2, w2) = (v1 + v2, w1 + w2), c(v1,w1)= (cv1, cw1).

Check axioms 1-4. Space Z is known as product V x W.


*my problem with these questions arise from the fact that it is simple to prove VS1 but I have no idea how to prove the other axioms like VS 2 or VS 4.
 
Look at #1. What would the additive inverse be equal to?
\(\displaystyle \begin{array}{l}
\left( {a,b} \right) + \left( {x,y} \right) = \left( {0,0} \right) \\
\left( {a + x,by} \right) = (0,0) \\
x = - a\quad \& \quad y = 0 \\
\end{array}\)
Does that fit the definitions?
 
thanks pka now i see how VS4 fails for question 1 and that question 1 is not a vector space. but im also wondering how do i test VS 2 for question 1 and question 2.
 
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