Math Is Fun Forum

beluga

Member

Registered: 2010-06-26

Posts: 8

Rearranging formulae

Q. Rearrange each of these formulae to make the pronumeral in the brackets the subject (all pronumerals represent positive numbers.

There were two more which I have not included because I think I got them right. I have trouble what to do first with these formulae like when to divide, take, add, multiply, factorise or expand.

X = C/(T-L)                 (T)

X= ab2  - 2ab      (a)
          3

T= 2π √(L/g)           (l)

1/x + 1/y + 2/z             (y)

Help is greatly respected and appreciated

Thank you

Last edited by beluga (2010-09-20 23:48:36)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Rearranging formulae

Hi beluga;

X = C/(T-L)                 (T)

I guess you want to solve for T

Multiply both sides by (T-L)

Divide by X.

Add L to both sides.

T= 2π √(L/g)           (l)

I guess you mean solve for L not l.

Square both sides to eliminate the radical.

Times by g.

Divide by 4 π^2.

Please check your other 2 questions as they are not  okay.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

beluga

Member

Registered: 2010-06-26

Posts: 8

Re: Rearranging formulae

Thank you for the help

I wrote the other questions incorrectly

X= ab2 ÷3 - 2ab      (a)
         
1/x + 1/y = 2/z        (y)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Rearranging formulae

Hi;

I think you mean this:

Pull out an a from both terms.

Divide and leave a by itself.

For the next one:

Subtract 1 / x:

Topsy turvy!

Times top and bottom by zx.

Clean up.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.