Math Is Fun Forum

Ahhh thanks!:)

Well, we only need one other vector, so we may as well do BC

So we now do a dot product between one vector in the plane and 'n' and set it equal to zero.  Do again for the second vector.

Now if I can choose any value for a then I may as well go with 1, which gets us:

Okay so let's choose:

Now, at this point the most sensible thing to do would seem to be to multiply n by 10, but I happen to know that the book's answer actually requires me to multiply by -10. Now, unless I'm very much mistaken, the values of n make no difference at all, but it'd be nice to get the book's value of n, just to tie it off nicely. So we have:

Which leaves me with something of a problem, because the correct answer should be 120

Of course, I'm perfectly happy to wait, especially for answers as instructive as yours. However, I'm surprised to here about the weather, it's very cloudy here on (presumably) the other side of Essex.

Oh, whoops, sorry, no I didn't I copied and pasted the matrix template for simplicity and forgot to change the entries! Sorry for the confusion, it should be the same as the last line of the preceding post, I'll just change it.

Hmmmm it's a tricky one, I copied out the question exactly as it stands in the book, but if it helps I can copy out the book's example of a problem which is similar to these questions, but not quite the same, perhaps that would shed some light:

Ahhhhhhh I see, thanks!!!

Ooooh that is, indeed, very nice, I must say, it is very clear and well-done. It is good to see it explained this way - of course I've come across it many times - but it was originally explained to me arguably less well.

Hmmm such an explanation may indeed be helpful - the reason why I've moved so far in so short a time is that my textbook assumes knowledge of chapters I haven't yet covered. Also, I'm sorry to hear that you're out of bandwidth but I would be happy to have a look, I don't quite know where you mean by 'teaching resources' however?

Hi Bobbym, I agree, instructive and well laid out, good quality as well - sometimes they can be difficult to read - thanks

Hmmm thanks Bobby, so could I then say:

Oh hi Bob Bundy, I didn't see your reply there, you replied just as I was, thanks a lot

Hi Bob, thanks again. Well the A-level mathematics examinations have changed a little in recent times, but the Edexcel board currently offers these units:

Core mathematics: C1, C2, C3 & C4
Further Pure mathematics: FP1, FP2 & FP3
Mechanics: M1, M2, M3, M4 & M5
Statistics: S1, S2, S3 & S4
Decision mathematics: D1 & D2

I'm not sure as to the number of possible combinations, but my school offers single maths: C1, C2, C3 & C4, along with either M1 & M2, or S1 & S2 (or, rarely, M1 & S1) depending upon the teacher and other subjects (i.e. those taking subjects such as physics would do mechanics and those taking subjects such as economics would do statistics, but this is not exact) and further maths: C1, C2, C3, C4, FP1, FP2, FP3, M1, M2, M3, S1 & S2 (and possibly S3, I'm not really sure). Anyway, last year I opted for single maths, however, matrices aren't covered until FP1 and FP3, but I wished to study them for their interest and use in mathematics and physics, as well as in order to understand another book, in which some key concepts are explained through matrices. So, I asked my teacher for help and he gave me a quick overview and the FP1 & FP3 textbooks, which I have since been working through - I'm hoping to begin linear transformations in 3-dimensions today, so no doubt I'll have plenty more questions for you . But yes, the eventual answer to your question is that I personally won't be taking an exam at the end (although one could) it is merely an academic curiosity.