Rearranging Formulas
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
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
