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D1 Maths, Edexcel

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Reply 20

Xtian

Thanks! I've also got D1 and S1 tomorrow!
Good luck to you too!

Reply 21

Slowbro93

Good luck everyone, but goin to be exhausted tomorrow, D1, S1 and Physics all in one day! FML

Reply 22

bijesh12

cpdavis

Good luck everyone, but goin to be exhausted tomorrow, D1, S1 and Physics all in one day! FML

I got D1 and Unit 1 Mechanics (OCR A Physics ) are u taking abt the same thing, if you are, then sfe.

Reply 23

DarkWarrior

In the Linear Programing, when using the objective line function, do you have to draw out lots of lines while you move your ruler?

Reply 24

Andy Ftw

DarkWarrior

In the Linear Programing, when using the objective line function, do you have to draw out lots of lines while you move your ruler?

One line is fine, as long as you clearly label it as the objective line, otherwise you'll get no marks. Also make sure it's of a reasonable size, eg. not way too small near the origin otherwise you'll probably lose a mark for that.

Reply 25

dcpower

Nope. Draw only 1! =)

Reply 26

TwirlGirl

For the Jan 2010 paper:

The markscheme for the flow chart puts all the answers in different lines :s-smilie:

could someone explain why?

For example when you found T=3400, they put R=7000 in the line below, and R>0 = Yes in the line below that.

Why?!

Reply 27

DarkWarrior

Thanks guys,
I just saw in the book a little bubble saying:
the objective line of the form P=ax+by
always passes through (b,0) and (0,a), should be useful to remember as well :smile:

Reply 28

Slowbro93

bijesh12

I got D1 and Unit 1 Mechanics (OCR A Physics ) are u taking abt the same thing, if you are, then sfe.

with physics, it;s unit one for edexcel. But it includes half mechanics, and half materials. Hoping for 90+ %. Good luck! :biggrin:

Reply 29

Xenomorph v2.1

do we need to know the handshaking lemma? It's easy to learn but my head will explode if I have to remember yet another algorithm, no matter how simple :dry:

Reply 30

Andy Ftw

Xenomorph v2.1

do we need to know the handshaking lemma? It's easy to learn but my head will explode if I have to remember yet another algorithm, no matter how simple :dry:

It's in the syllabus so you do need to know it.. Thoughtit is very very unlikely it will come up. Though it's best to know it cause you never know..

It's pretty simple though, for every arc there must be two valancies contributed to the graph, so 2 x arcs = valancies, so total amount of valancies is always even, and if there is a odd valancy for one node there must be a paired node that also has an odd valancy so there is always an even number in total .. :P:

Gl tmoz :smile:

Reply 31

semolina pilchard

Quick question, for the first fit decreasing bin packing algorithm would you be expected to sort the numbers into descending order first using a quick sort for example, or would you only have to do so if they explicitly asked you to. In other words can you just write down the series in descending order and go from there unless asked?

Reply 32

TwirlGirl

semolina pilchard

Yes

Reply 33

semolina pilchard

TwirlGirl

Yes

Thanks

Reply 34

Xtian

TwirlGirl

For the Jan 2010 paper:

The markscheme for the flow chart puts all the answers in different lines :s-smilie:

could someone explain why?

For example when you found T=3400, they put R=7000 in the line below, and R>0 = Yes in the line below that.

Why?!

I know right!

Anyway, I'm just going to do it how it's always been done. :smile:

Reply 35

TwirlGirl

Xtian

I know right!

Anyway, I'm just going to do it how it's always been done. :smile:

Is that not right then?

And also;

I always get SO confused with things like y<2x or 2y<x ...how would i write that in words? Any easy way to remember which way around it goes?

Reply 36

Munster

Xenomorph v2.1

do we need to know the handshaking lemma? It's easy to learn but my head will explode if I have to remember yet another algorithm, no matter how simple :dry:

Omigosh I totally forgot what that was! :eek3:

Reply 37

TwirlGirl

typewriter

crocodiles. in the first one (y is less than 2x/2x is greater than y), the 2x OMNOMNOMs the y :p:

(it's bigger on the 2x side) and then on the graph, you work out which side of the line you want by picking a point and then seeing if it fits the inequality

edit - yeah I got confused doing that jan 2010 question as well. ended up with 3 lines or something

second edit - got some questions - on one paper i was trying to draw a profit line but i could get a good one that passed through the feasible region. does it have to? also when using the vertex method of finding the maximum (or minimum), what if the values have to be integers, and the vertex that gives the maximum has non-integer co-ordinates?

I don't draw profit lines..get a bit confused with what they actually are :p:

But the second non-integer bit!!!! I got so confused too...should i round up or down or what?! Because you can't have .3 of a cupboard! Basically i have no idea :frown:

What are you going to do if we have to do a flowchart table? Will you put them in the same row or stagger the values down the table?!

Reply 38

Dr WestwooDD

TwirlGirl

I don't draw profit lines..get a bit confused with what they actually are :p:

But the second non-integer bit!!!! I got so confused too...should i round up or down or what?! Because you can't have .3 of a cupboard! Basically i have no idea :frown:

What are you going to do if we have to do a flowchart table? Will you put them in the same row or stagger the values down the table?!

You are meant to stagger them, but I sat the Jan 2010 paper and didn't stagger the values (I only used like 3 lines), and when I got my paper back I still got full marks for that question :smile:

Reply 39

DarkWarrior

TwirlGirl

I don't draw profit lines..get a bit confused with what they actually are :p:

But the second non-integer bit!!!! I got so confused too...should i round up or down or what?! Because you can't have .3 of a cupboard! Basically i have no idea :frown:

What are you going to do if we have to do a flowchart table? Will you put them in the same row or stagger the values down the table?!

For this, you would find out the coord of the max/min value.
Say its (33.6,77.1) then you would test out the 4 corner vertexes
in this case, you'll have to find (33,77),(34,77),(33,78),(34,79)
and see if they're in the feasible region and which one is is the max/min out of those 4.
hope this helps :smile: