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Edexcel FP3 June 2015 - Official Thread

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Reply 300

Boop.

Can someone explain how they have found the normal to the plane in Qn 7a P6 JUNE 2003

P6 - JUN03 - QP.pdf55.4KB

P6 - JUN03 - MS.pdf160.1KB

Reply 301

BP_Tranquility

For d, I did AQ²=14+(2rt35)² . Then square rooted that. But that gives 4root21 instead of the answer which is supposedly root 154 . can someone help?

EDIT: did it - I did 14² instead of (root14 )² :colondollar:

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(edited 8 years ago)

1434729655085.jpg35.9KB

Reply 302

math42

Original post by Boop.

Can someone explain how they have found the normal to the plane in Qn 7a P6 JUNE 2003

I'm pretty sure that there is a typo and on the exam paper it should be -i + 5j + 3k rather than -i + 2j + 3k

Reply 303

elliemoriarty

Original post by Boop.

Can someone explain how they have found the normal to the plane in Qn 7a P6 JUNE 2003

I think the paper's got a typo. Where it states the equation of the line the 2j should be a 5j. Then you use that line's direction as the normal!

(edited 8 years ago)

Reply 304

ninjasinpjs

http://imgur.com/m3DlMGQ

Can someone explain 2c, if i was to lets lets say z = 3 i would get a different eigenvalue, but the mark scheme seems to say that i cannot do this.

Thanks

Reply 305

DanTheMan358

Original post by physicsmaths

Na didn't bang it one of my solutions had errors so I'm sitting in 70s which might not even get me a 1. My partials were **** aswell.

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Well still much better than a lot of people. Don't worry you'll still make your offer :smile:

Reply 306

username1162972

Original post by DanTheMan358

Well still much better than a lot of people. Don't worry you'll still make your offer :smile:

Hope so. I'm in the high 50s/ low 60s in III, borderline in both :frown:

. WBU what's your offer?

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Reply 307

DanTheMan358

Original post by physicsmaths

Hope so. I'm in the high 50s/ low 60s in III, borderline in both :frown:

. WBU what's your offer?

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Got Warwick firmed, Step I weren't great and II was pretty much a disaster. So will likely end up at insurance :frown:

. Should have put more effort into step but I wanted nice A levels lol.

Reply 308

ninjasinpjs

can some one explain how that get (1 + x^2 ) on the NB line

http://imgur.com/FMCaUYQ

Reply 309

BP_Tranquility

What are the formulas for surface area/volume by revolution around the y axis?

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Reply 310

username1162972

Original post by DanTheMan358

Got Warwick firmed, Step I weren't great and II was pretty much a disaster. So will likely end up at insurance :frown:

. Should have put more effort into step but I wanted nice A levels lol.

I was opposite put all my time into step and flopped physics, maths and fm are chilled though.

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Reply 311

math42

Original post by BP_Tranquility

What are the formulas for surface area/volume by revolution around the y axis?

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They're in the formula booklet; volume of revolution is in C4 though.

Reply 312

math42

Original post by ninjasinpjs

can some one explain how that get (1 + x^2 ) on the NB line

http://imgur.com/FMCaUYQ

They multiplied the numerator and denominator by (1 + x^2)^(1/2)

Reply 313

ninjasinpjs

Original post by 1 8 13 20 42

They multiplied the numerator and denominator by (1 + x^2)^(1/2)

i know they done that but when i get the dy/dx expression and multiply out the two fractions i get the denominator as 1 where is should be (1 + x^2 ), it would be really helpful if you could show me how they got that.

Reply 314

BP_Tranquility

Original post by 1 8 13 20 42

They're in the formula booklet; volume of revolution is in C4 though.

The ones in the booklet are for rotation around the x axis, what about around the y axis?

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Reply 315

math42

Original post by ninjasinpjs

You should get that. The NB line is only dealing with the second fraction. If you simplify the expression you have you will obtain the necessary dy/dx.
That NB line just draws attention to another way someone may have approached the question, by first simplifying the second fraction.

Reply 316

BP_Tranquility

Do we need to know about hyperbolae and ellipses with foci on the y axis?

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Reply 317

math42

Original post by BP_Tranquility

The ones in the booklet are for rotation around the x axis, what about around the y axis?

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Well I don't know if they can ask that. For volume they specifically say that it won't be rotated about the y-axis but they admittedly don't say that about surfaces and arc length. Nevertheless they would be exactly the same except you would swap all the x and y values around and use the upper and lower y values rather than upper and low x values; so (dx/dy) instead of dy/dx, of course integrate with respect to y, 2xpi instead of 2ypi and so on. The parametric variants wouldn't change.

Edit: there is one difference with surface area mentioned in the textbook; you can (also, the other formula still works) find the surface area for rotation about the y-axis by simply swapping out y for x in the (2piy) bit and leaving everything else the same.