rearranging formulas

[cocaine]

ahh i cant stand these haha they make me want to tear my hair out.

im very good with other aspects of maths, just so you know im not a complete idiot haha. but rearranging formulas to make one letter the subject of the formula is my downfall.

heres an example:
Make q the subject of the formula

P = 2q + 10

can anyone write down steps for what you need to do for that? thanksss

edit: hang on, is this right

p-10=2q

so q = p-10 OVER 2

?

[Jesus-Egg]

Yes, that is correct.

Rearranging formulae is usually fairly simple. Just keep practicing until you get the hang of it, and you'll be fine. You just need to remember to follow the following steps:

If, for example, you want to make a the subject:

- Multiply through to get rid of any fractions

- Collect all of the terms with a in on one side of the equation, and move all the terms without an a to the other side

- Factorise, so you have a multiplied by something, which i'll call B

- Divide through by B, and you're done

Example:

c = (2a -3b)/5a

and you want to make a the subject

- Multiply by 5a to get rid of the fraction

5ac = 2a -3b

- Collect all the as to one side of the equation

2a - 5ac = 3b

- Factorise

a(2 - 5c) = 3b

- Divide

a = 3b/(2 - 5c)

[Barmi]

Get used to rearranging equations... you need to do it for a lot of maths past GCSE (if you plan on pursuing it).

The best thing to do is practice. Do plenty of difficult questions until you are sick to death of them. You will feel like you are invincible. Then you face Integration and realise all is lost.

[Supersam]

Get used to rearranging equations... you need to do it for a lot of maths past GCSE (if you plan on pursuing it).

The best thing to do is practice. Do plenty of difficult questions until you are sick to death of them. You will feel like you are invincible. Then you face Integration and realise all is lost.

And then you realise that maths beyond GCSE is just crazy and Integration is only the start of your worries.

[Barmi]

And then you realise that maths beyond GCSE is just crazy and Integration is only the start of your worries.

I found everything easy at A-level bar Integration.

[AJKHoosier1]

if you can't rearrange formula's, you are screwed when it comes to relativity
and the one itt is like omg ezz

[le harry]

I found everything easy at A-level bar Integration.

you noob integration is easy. matrices :@

[luce]

Get used to rearranging equations... you need to do it for a lot of maths past GCSE (if you plan on pursuing it).

The best thing to do is practice. Do plenty of difficult questions until you are sick to death of them. You will feel like you are invincible. Then you face Integration and realise all is lost.

you don't need to that much to pass GCSE! Also A level isn't much harder then GCSE. Not what i've done of it anyway, i haven't started C4 yet though :rolleyes:

[Soka]

Hardest topic i've seen in this thread in my opinion is matrices by harry. Comes up in FP1 in the UK.. matrices row operations are awful.

Barmi, i've sent you another PM regarding uni's!

Cocaine, just remember that whatever you do to one side you must do to the other.

Also order is important when rearranging:

Addition and Subtraction first
then
Division and Multiplication.

The key really is to practice, practice and practice then it will all just be done naturally

So using yours as an example

P = 2q + 10
P - 10 = 2q + 10 - 10 (subtraction first.)
(2q)/2 = (p - 10)/2 (division last)
Hence;
q = (p - 10)/2

i've included the strike through parts to show that the operation has being carried out on both sides. I'm sure you don't need the strikethrough parts!

[--ss--]

You basically move figures to the other side by doing the inverse operation to it, so lets say on the right hand side you have a +10, as you want to make the letter on the left hand side the subject you gotta move the +10 to the other side so you'll make it -10. actually i'm not too sure what i'm talking about, it's quite easy when you get the hang of it, have you tried using mathswatch on the net somewhere?