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# Edexcel A2 C4 Mathematics June 2015 - Official Thread Watch

1. (Original post by Ripper Phoenix)
okay and what if it said parallel to x axis?
numerator zero.
2. Could someone please post the June 2015 C34 ial mark scheme please!
3. (Original post by Humbers)
Ok so when the tangent is parallel to the Y- axis, it means the tangent is vertical and therefore has an 'infinite' gradient

The expression for dy/dx is -(2x+4y)/(4x+2y) for dy/dx = infinity the denominator must be equal to zero as anything divided by zero is undefined/infinite

so then you get 4x + 2y = 0 y = -2x substitute that into the original equation to solve and get the co-ordinates
okay but what about the tangent parallel to the x axis? then?
4. (Original post by MasonPye)
Could someone please post the June 2015 C34 ial mark scheme please!
5. (Original post by TeeEm)
numerator zero.
aha okay...

you're a man of very few words

but my teacher said we equate dy/dx to zero if it is parallel to x axis.. is this incorrect?
6. (Original post by marco cb)
Yep, before I head to school, any last key points to remember in the exam, anyone?
if in doubt, walk out

jk you gotta pass, we all gotta pass!! good luck!!!!
7. (Original post by marco cb)
Yep, before I head to school, any last key points to remember in the exam, anyone?
iboprufen, imodium, glucose tablets, indigestion tablets, asthma pump (optional), water, tissues, toilet paper, disinfecting gel, ...
8. (Original post by Ripper Phoenix)
okay but what about the tangent parallel to the x axis? then?

Parallel to the x-axis means a horizontal line, so no gradient.

therefore the numerator must be equal to zero
9. (Original post by TeeEm)
look at related rates book Q30
Do they have to ask for permission or something? or do they just swap values and rip the Q off you?
Spoiler:
Show
got a related rates Q in particular that you would advise I do before todays exam? Found the one in question above fine - although i did not connect it in the long chain of 3 if that makes sense, I brought out the dv/da separately
10. (Original post by Ripper Phoenix)
aha okay...

you're a man of very few words

but my teacher said we equate dy/dx to zero if it is parallel to x axis.. is this incorrect?
when I was at school (Year 7) we used to chant ...
if a fraction equal zero the only thing that can make it zero is its numerator ...
if a fraction equal zero the only thing that can make it zero is its numerator ...
if a fraction equal zero the only thing that can make it zero is its numerator ...
if a fraction equal zero the only thing that can make it zero is its numerator ...
Attached Images

11. (Original post by Ripper Phoenix)
aha okay...

you're a man of very few words

but my teacher said we equate dy/dx to zero if it is parallel to x axis.. is this incorrect?
Yes dy/dx would equal zero

in this case the only way dy/dx can = 0 is if the numerator is equal to zero as you can never divide something to get zero
12. (Original post by asjdj)
When you realize you're on your period few hours before the exam.. nooooooooooooooooooooooooooooooo ooooooooooooo
wtf?
13. Looks like I got 62/63 marks in C3, if Arsey's right and 64 marks is 90UMS there's still some hope for an A*, here's to hoping
14. (Original post by Ripper Phoenix)
if in doubt, walk out

jk you gotta pass, we all gotta pass!! good luck!!!!
If I see a tricky ass question 1 that I can't answer, I will most likely have no option but to walk out. But ha thanks - Good luck to you too!
15. Can someone explain to me how to reflect a point in a line please?
16. (Original post by TeeEm)
iboprufen, imodium, glucose tablets, indigestion tablets, asthma pump (optional), water, tissues, toilet paper, disinfecting gel, ...
Check, check and check.. ran out of toilet paper though,
17. (Original post by Gilo98)
Do they have to ask for permission or something? or do they just swap values and rip the Q off you?
Spoiler:
Show
got a related rates Q in particular that you would advise I do before todays exam? Found the one in question above fine - although i did not connect it in the long chain of 3 if that makes sense, I brought out the dv/da separately
triple rate is the sensible way, although it can be done as a double
18. Does anyone have any tips for sketching vector diagrams to make them easier to understand? Vectors are the one area I just can't seem to get my head round...
19. (Original post by TeeEm)
when I was at school (Year 7) we used to chant ...
if a fraction equal zero the only thing that can make it zero is its numerator ...
if a fraction equal zero the only thing that can make it zero is its numerator ...
if a fraction equal zero the only thing that can make it zero is its numerator ...
if a fraction equal zero the only thing that can make it zero is its numerator ...
i really need to meet you in real life

thanks tho
20. (Original post by marco cb)
Check, check and check.. ran out of toilet paper though,
what if you get the sh..., you run to the toilet and there is none?

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