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 Nov 26 accepted Proving statements related to open sets Nov 25 revised Proving statements related to open sets edited body Nov 25 comment Proving statements related to open sets thanks for the pointers, i edited the part where i had incorrectly written $V \cap V$. ok that makes a lot more sense when it comes to (i)! as for (iv) unfortunately i still can't think of a way to get a closed interval as an intersection of open ones.... Nov 25 awarded Editor Nov 25 revised Proving statements related to open sets edited body Nov 25 asked Proving statements related to open sets Nov 25 accepted Show that this is a vector space and determine the dimension Nov 25 comment Show that this is a vector space and determine the dimension @Arturo: wow, thank you! this is extremely helpful, i'll be digesting it for a little while... Nov 24 comment Show that this is a vector space and determine the dimension @Arturo that'd be great, yeah it's absolutely no rush, but thank you very much. Nov 24 accepted which of the following are linear mappings? Nov 24 comment which of the following are linear mappings? right, that absolutely makes sense to me. i think the only thing i'm still not understanding is how to interpret (c) and (d) (without even trying to test if they are linear). i wasn't sure if the brackets around $t$ meant something in particular and i need to do some reviewing/learning of converging sequences, limits, etc... Thanks a lot for the response! Nov 24 comment Show that this is a vector space and determine the dimension Let $T,U \in \mathbf{V}$, $T(a,b,c,d) + U(a,b,c,d) = (T+U)(a+a, b+b, c+c, d+d) \Rightarrow (T+U) \in \mathbf{V} \Rightarrow (T+U)$ is a linear map?? just to be clear, must the input for both $T$ and $U$ be the same? Nov 24 comment Show that this is a vector space and determine the dimension @Arturo so i think it's progress that i am seeing this as the set of linear maps from $\mathbb{R}^{4}$ to $\mathbb{R}^{2}$ for which $f(v)=0$. it wouldn't be that difficult for me to accept the properties of a vector space, but i find it very difficult to begin proving that they are true. for instance to 'prove' that $T + U$ are linear whenever $T$ and $U$ are linear, i feel like i would simply be restating using symbols if i were to write something like: (continued) Nov 24 revised which of the following are linear mappings? edited tags Nov 24 comment Show that this is a vector space and determine the dimension @Willie thanks for the hint, i think i understand why the linear map is the set of $4 \times 2$ matrices. however i must be missing something when i try to thing of the general form of a matrix you describe since i would thing matrix $A$ could be full of zeros.. Nov 24 comment Show that this is a vector space and determine the dimension @Rahul thanks for the comment, it definitely helps to clarify my conception of the given information! Nov 23 asked Show that this is a vector space and determine the dimension Nov 23 comment Showing that an equation holds true with a Fibonacci sequence: $F_{n+m} = F_{n-1}F_m + F_n F_{m+1}$ In any case it was good to try to see it from another angle, although to be honest, i'm still having some trouble really visualizing this, hopefully it hits me later... and yes the matrices seem really efficient but at least for me they still look like magic ;) Nov 23 accepted Showing that an equation holds true with a Fibonacci sequence: $F_{n+m} = F_{n-1}F_m + F_n F_{m+1}$ Nov 23 comment Showing that an equation holds true with a Fibonacci sequence: $F_{n+m} = F_{n-1}F_m + F_n F_{m+1}$ @Chandru1 thanks a lot for the help i think i'm slowly starting to understand this stuff. To prove it with $n=2$ i simply broke $F_{n+2}$ down into $F_{n+1} + F_n = F_n + F_{n-1} + F_n$ which is what i obtained when substituting $n=2$.