Math People- Help, Urgent!

[Legolas]

uno mas problemo, senor profesor

x+2y= 4
y^2- xy= 7

[Spider_dude]

do this one yourself or you'll never learn and fail all your exams and have to take a job working voluntary for a sex education scheme for the council.

[J'Pol]

Originally posted by Lamsey+15 March 2004 - 03:44--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Lamsey @ 15 March 2004 - 03:44)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-4play@15 March 2004 - 01:40
a masters hey, /me adds your email to my list of people i can bug for help.

No, I&#39;m doing... um... a PhD in History of Turnips, that&#39;s it&#33; [/b][/quote]
At a Poly

[Nimdock]

Hey Legolas that&#39;s some basic stuff, just follow what Lamsey did, if you keep asking for the solutions you won&#39;t learn anything.

[Lamsey]

Originally posted by Legolas@15 March 2004 - 01:51
uno mas problemo, senor profesor

x+2y= 4
y^2- xy= 7

Gawd damn it, I was just about to go to bed

Ok...

x + 2y = 4

so

x = 4 - 2y

so

y^2 - xy = 7

is

y^2 - y(4 - 2y) = 7

which is

y^2 - 4y + 2y^2 = 7

which is

3y^2 - 4y - 7 = 0

which is

(3y - 7)(y + 1) = 0

so

y = 7/3 or y = -1

so

when y = 7/3, x = (4 - 14/3) = -2/3

when y = -1, x = (4 - -2) = 6

so answers are (-2/3, 7/3) and (6, -1)




No more, I&#39;m off to bed. Do the rest yourself

[Nimdock]

Give a man a fish...

[J'Pol]

Originally posted by Nimdock@15 March 2004 - 04:00
Give a man a fish...

Excellent point.

[james_bond_rulez]

Originally posted by Nimdock@14 March 2004 - 18:00
Give a man a fish...

he&#39;s gonna want a boat....

[Legolas]

lol thanks for all the help lamsey and others. no more. thanks again

[4th gen]

Can&#39;t sleep

Ok, so now that this is homework corner, let me ask a question (physics, not maths):

"1 litre of water is heated from 20 degrees celsius until it has boiled and completely evaporated. The steam then condenses onto a second surface at 20 degrees celsius. How much energy has been transferred from the first surface to the second?"

Now, the way I&#39;m thinking, it&#39;s just gonna be the specific heat needed to cool the water from 100 degrees celsius down to 20 degrees (i.e. 83600J), plus the latent heat of vapourisation of water (i.e. 2260000J). Any thoughts though people?