rearranging formula

Algebra Rearranging Formulas EASY – When you know how!!!

Rearranging Formulas

(Transposition of formulae)

RULE 1 We can pick ‘terms’ up and move them across the ‘=‘ sign quite easily but remember that they must do the opposite on the other side!!

E.g.

Make R the subject THINK:

V= I R

V=IR

What is the I

R

To get on it’s own, we need to get rid of the

doing to the R?

I

If it is multiplying on RHS, on LHS it will do opposite -

dividing

Rearranging Formulas

(Transposition of formulae)

Another…… Remember, we can pick ‘terms’ up and move them across the ‘=‘ sign quite easily, but remember that they must do the opposite on the other side!! E.g.

Make F the subject

P =F A P=F A

To get F on it’s own, we need to get rid of the A

THINK: What is the A doing to the F?

If it is dividing on RHS, on LHS it will do opposite -

multiplying

Rearranging Formulas

(Transposition of formulae)

Make a the subject of the formula

v = u + at

- v = u +at v -u =

at

Get rid of the u

, take it to the other side and make it a minus Take the t across and divide!

Getting harder!!! (not really) RULE 2

Dealing with fractions

E = 1 mv 2

2 Think of them as one number divided by another number.

To get rid of the 2, take it across and multiply

Getting harder!!! (not really) Squares and square roots So….make v the subject

RULE 3

2 E = 1m v 2 2 E = 1 mv 2

2E = m v

2

2E = m

2

v

1. Deal with the fraction. 2. Move the m

3. Then deal with the square

Rearranging Formulas Now for a toughy! Make l the subject.

T= 2π

l g

T = 2π

l g

2

l g

2

l g

T = 2π

( ) T = ( 2 π)

(Transposition of formulae)

Rearranging Formulas Rule 4

(Transposition of formulae)

These babies need to be factorised!

Make x the subject

A = 2x

+ xy

Hmm, x appears twice, I only want it to appear once!

FACTORISE