can someone explain transposition of formulae to a confused builder type ?

Answer 1

Do not think of a formulae in terms of transposition, think of it in terms of an old-fashioned balance like this:
http://en.wikipedia.org/wiki/Image:Balance_%C3%A0_tabac_1850.JPG

With the sign "=" as post and a left and right hand side.

Now, whatever you do, you have to apply it on both sides in order to keep the balance in balance. You may add, subtract, multiply by, divide by or do even more complex things like squaring, drawing roots, differentiate or integrate. No problem, as long as you do equally on both sides, There is just one thing strictly forbidden to do with an equation:

Never ever divide an equation by 0 or something equal to zero.

It will kill the equation, respectively destroy the balance. Boom.

Now, to be honest: there are physicians for equations who are able to cure even killed equations by sending them to a hospital and applying L'Hopital's rule, but for now that is too advanced - unless you want to be a physician for equations needing a cure.

Ok, practice. Assume we have

5 * x - 10 = 0

and we want to find out what x is. Then this "-10" on the left hand side is really irritating. Now, if we just would add 10, then the 10 on the left hand side will go away because "-10 + 10" is 0. But: we have to add 10 on both sides in order to keep the balance:

5 * x - 10 + 10 = 0 + 10

or in other words:

5 * x = 10

Hmmm, now I find this 5 on the left really annoying. If deviding by 5 it would go away because "5 / 5" is 1 and "1 * x" simply is x. But; in order to keep balance I have to do the same on both sides:

5 * x / 5 = 10 / 5

resulting in

x = 2

Wow, I found what x is. Did I really? Let us test:

5 * x - 10 = 0

Now, if x is 2 then we have

5 * 2 - 10 = 0

respectively

10 - 10 = 0

or

0 = 0.

That definitely is a well balanced identity.

Answer 2

A formula will contain a number of elements.
The formula can be changed around in different ways.
As an example, suppose a formula has four factors or elements. Sometimes one of the factors on it's own is required. This factor is known as the subject factor. The formula then is arranged to get the subject factor on one side of the equal to sign and everything else onto the other side.

Examples:

Make R the subject.
RT = XP/ D
R = XP/ DT


Make P the subject.
RT = XP/ D
RTD = XP
RTD/ X = P


Make T the subject.
2T - X = 10
2T = 10 + X
T = (10 + X)/ 2

Answer 3

Transposition Of Formula

Answer 4

I don't think there's a simple answer to your question, but I'll try to give you a general idea.

A formula will enable you to find some information from other information which you have. There will be a "regular" way of expressing that formula with just one symbol on one side of an equals sign (usually the left-hand side) and the relevant way of combining the other information on the other side of it.

For example, the distance (D) covered by something travelling at a particular rate (R) in a given time (T) can be calculated according to the formula

D = RT

If you happen to have values for D and R, but want to find the relevant value of T, then it can be done by transposing the formula to make T (the missing information) the "subject" of the formula.
In this particular example, that would be

D/R = T

This is a very simple example, and I hope I've managed to give you some idea.

Answer 5

Sure Bro (yeah, I'm a Kiwi). To rearrange a formula, start simple...

Take, for example, 3 = 6/2 (i.e. 3 = 6 divided by 2).

Now try re-arranging it a little bit: if you take the 2 over to the other side of the equals sign, you'd get: 2 x 3 = 6. Now, write this out on paper. It'll make a lot more sense. Then try re-arragning it again; for example: swap the bottom number (2) with the number on the other side: and you get: 2 = 6/3. (You can do the same with other equations - just check it against something simple like this one above. If it holds true, then its right). Now this seems simple, but its actually the basis of some very complex equations.

Now there's more (by the way, I did 5 years uni/varsity, incld advanced engineering mathematics, etc - I'm an engineer, for the last 11 years :-)).
Try 3 = 6/2. Now subtract 3 from each side: what do you get ? You get: 3 - 3 = (6/2) - 3. That is, you get 0 = 0. Yes, you took 3 away from each side. Point is, what you do to one side of the '=' sign, you MUST do to the other.

Hope this helps, buddy. :-) Cheers. :-) Glen
Email me if you're still needin' help on this. Cheers.

Answer 6

Transposing Formulas

Answer 7

Remember The LEFT HAND SIDE {LHS}Always MUST Equal RIGHT HAND SIDE {RHS}

So whatever you do to one side to 'get rid' of a term you MUST do to the other side

Let us look at an example

zevB = mv²/r

So to write expression in terms of 'm' [or leave 'm' alone on LHS]
You divide both sides by v² and at the same time multiply by 'r'

So

m = zevBr / v²

Simplify further

On RHS term v/v²
becomes 1/v

so m = zeBr/ v


Hope this helps :-)