science and maths revision help.

[mollykins]

I have already found something i'm stuck on and will keep this thread open incase i'm stuck with anything else, so please no spamming, get straight to the point.

1) what TWO thing does the dynamic equilibrium sign mean? the reaction is reversible? but what else? after a certain time the same amount of products and reactants are being made?

[mollykins]

would you double eevrything so it equalls 1?

[mollykins]

then times by the denominators, then factorise, then get rid of whats inside the brackets?

[jackthehat]

It's still not actually a subject called 'triple physics' though, is it ?

If you have genuine revision questions, by all means ask.............

[factor-fiction]

mollykins-you try this and see what you get

multiply each term by (y+7)(y+6)

that gives 3(y+6)-(y+7)= (y+6)(y+7)/2
Then multiply both sides by 2
Then expand brackets, rearrange and find y
That will give a quadratic.
Then work it out from there. I've not done it yet. I need some paper

[mollykins]

well triple physics was 5 lessons a fortnight, of which we swapped between biology chemistry and physics.

and i don't know hwo to do this one either;

you are given the following identity x^2-ax+144 (definatly equals sign) (x-b)^2

would you square rooot everything first?

[mollykins]

thanks factor.

[dothawkes31]

yes that would work, personally I would use a scientific calculator though but

[jackthehat]

You really don't like being contradicted, do you ?

[dothawkes31]

There is double science though, most GCSE candidates do that, how do they justify dedicating a science teacher to a triple physics student when the rest doing science will need their time too?

[factor-fiction]

If it's an identity it will be an equals sign with three lines not two

Don't square root it-just expand all brackets then compare coefficients of x², x and the constant
see where that gets you

[mollykins]

yeah but while we were doing triple science other optional subject were running for ym year group such as art (which was in all the pools and also a technology, probably a language and a couple of other things like gcse pe and ict)

[mollykins]

aahhh thats where i was going wrong.

[factor-fiction]

on your identity one I get x² -ax +144 = x² + b² -2bx
Comparing constants gives b²=144 so b = + or - 12
Comparfing coefficients of x gives a=2b=24

[factor-fiction]

...and a=-24

[mollykins]

you lost me kind of on the second line . . . . .this is why it'll be down to luck if i get an a* question on the exam that i can answer.

[mollykins]

Some a* stuff i can do easily and can't see what's ahrd about it and other stuff makes me go 'meh.'

[factor-fiction]

,,,,3,,,,,-,,,,,1,,,,,= 1
,------,,,,,,-----,,,,,,---
,,y+7,,,,,,,y+6,,,,,,,2

I have got an answer of y= -5 and -4

Is that what you get?

[mollykins]

yep huray!

[factor-fiction]

You say I lost you on my second line.
I'll try again then
I had:
x² -ax +144 = x² + b² -2bx
I'll rearrange that a bit to become:
x² -ax +144 = x² -2bx + b²
If you compare the two sides you can see they would be identical if b² =144 and if the two coefficients of x (-a and -2b) are the same - i.e. if a=2b

Does that help?