Let us look at all the axioms of a vector space and see which axioms are broken.
1) Associativity<span> of addition
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It's trivial to see this one holds.
2)</span>Commutativity<span> of addition
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<span>This one holds.
3)</span>Identity element<span> of addition
</span><span>This means that we have zero vektor. It is pretty obvious we do, it is (0,0).
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4)Inverse elements<span> of addition
</span>This means that for each element in V there exists element -v such that v+(-v)=0.
We do have inverse elements.
5)Compatibility<span> of scalar multiplication with field multiplication
</span>This one holds.
6)<span>Identity element of scalar multiplication
</span>Identity element of scalar multiplication is simply 1.
7)Distributivity of scalar multiplication with respect to vector addition. Let's look at the definition.
Now let's look at the example:
This one hold too.
8)<span>Distributivity of scalar multiplication with respect to field addition
</span>Definition of this one is:
Let's take a look at the example:
So this one doesn't hold.
The final answer would be distributivity of scalar multiplication with respect to field addition.
Please note vectors, in this case, are (a,b) and that I did not use the dot to indicate scalar multiplication.