This discussion is now closed.

Check out other Related discussions

Edexcel C4 June 2009 Thread :)

if

e^{x}

= u- 1

then does

e^{2x}

=

(u-1)^2

?

abit confused :o:

Reply 641

fn_101

10

My Alt

You can choose with the two. You can divide by it, or leave it, you will still get the same answer.

Ah, okay! Thank you so much :smile:

Reply 642

Waterstorm

16

fn_101

But in the mark scheme it says you leave the 2 up and integrate with respect to dt, so get 2t + c. Can you do it either way then?

Yeah, it's the same. Sorry, I thought you said 'what if the 2 isn't attached'.

Reply 643

My Alt

12

candle

if

e^{x}

= u- 1

then does

e^{2x}

=

(u-1)^2

?

abit confused :o:

I tentativly say "yes." You have squared both sides correctly, but you must remember that when squaring you create extra solutions. The second statement implies that

e^{2x}

is equal to positive u-1 and negative u-1. So be careful!

Reply 644

bnasir

candle

if

e^{x}

= u- 1

then does

e^{2x}

=

(u-1)^2

?

abit confused :o:

yes... =)

e^{2x}

is same as saying

x^2

if

e^{x}

is

x

=)

Reply 645

Little_Jacob

I'm going in for last minute prep work now so I hope it's a nice paper today.

Lest we all achieve our true potential :biggrin:

*signs out

Reply 646

aayman_farzand

Leaving for the exam venue now. Best of luck guys.

Reply 647

fn_101

10

Waterstorm

Yeah, it's the same. Sorry, I thought you said 'what if the 2 isn't attached'.

No problem - thank you so much for your help :smile:

Reply 648

bnasir

can anyone tell me the formulas i need to know for connected rates of change?

because at times for exam, it asks for u have to work out Area of sphere, cone ... will the formula for their areas and volumes be given in exam or do u have to know them? if so, which ones!?

Reply 649

candle

ok thanks ,
I am very scared I dont expect too much just a c will be fine but i hope i dont do mistakes on the questions that I can do so I get full marks on them but I will try to atleast attempt most of them.

Good luck everyone.

Reply 650

Kaz310

gd luck jacob...let me knw how it goes after

candle same here i need a high c or a b to get a b overall....arghh gd luck rest of you.

Reply 651

lilpenguin

1

Ahhhh it's approaching, the thing im so scared about is all these past papers could be pointless if they just word those questions in a hard way!

I really hope they give us a differential one instead of a shape and asking us to show that something is something! :P

Reply 652

Waterstorm

16

bnasir

can anyone tell me the formulas i need to know for connected rates of change?

because at times for exam, it asks for u have to work out Area of sphere, cone ... will the formula for their areas and volumes be given in exam or do u have to know them? if so, which ones!?

The volume for anything that's a pyramid-kinda shape, like cones, is always 1/3 times the area of the base times their height. It's always 1/3.

Reply 653

mathslover786

how would u go about duin jan 09 Q5???

Reply 654

Kaz310

mathslover786

how would u go about duin jan 09 Q5???

easy, first u differentiate it it with respect to x. so use implicit differentiation.

then to find the y value, plus x into the original equation to find coordinates.

and for part b plus in both y and x values into the differentiated equation to find your gradient.

woops sorry that jan 08 lol...ill have a look...

argh why have u given me a rates of change question! lolz

ask the alt! lolz sorry

Reply 655

bnasir

thxs waterstrom...

btw how do u prove that two vectors are skew?

Reply 656

mathslover786

Kaz310

easy, first u differentiate it it with respect to x. so use implicit differentiation.

then to find the y value, plus x into the original equation to find coordinates.

and for part b plus in both y and x values into the differentiated equation to find your gradient.

woops sorry that jan 08 lol...ill have a look...

argh why have u given me a rates of change question! lolz

ask the alt! lolz sorry

you are on about a totally different question...