The document discusses rearranging formulas by making a different variable the subject of the formula. It explains that the process is similar to solving equations, where the same quantity is added or subtracted to both sides, or both sides are multiplied or divided by the same quantity. Examples are provided of rearranging formulas by changing the operations to make a specified variable the subject. The practice problems ask the reader to rearrange several formulas by making the variable listed at the end the subject of each formula.

1. 4/27The Perfect Partner for your Digital Business
Mathematical Skills II
Rearranging Formulas
Pro. Ignacio Anguera
Colegio Real de Panamá

2. 4/27
Re-write a formula in terms of
another letter.
THE UNDERLYING PRINCIPLE
A formula is a mathematical equation containing two or
more letters.
REARRANGING
FORMULAS
You will be familiar with the formula for the area of a circle
which states:
in which case we would say that A is the subject of the
formula
A = π r2
Alternatively, we could have written the formula as:
𝑟 =
2 𝐴
𝜋
in which case we would say that r is the subject of the
formula

3. 4/27
Re-write a formula in terms of
another letter.
CHANGING THE SUBJECT OF A FORMULA
The rules are the same as when we solved equations except
we do not end up with a solution but with another formula.
REARRANGING
FORMULAS
• add or subtract the same quantity to or from both sides
• multiply or divide both sides for the same quantity
• square and square root are inverse functions (same as
cube and cube root).
Example 1: Addition/subtraction a + b = c + d
In each case, make -a- the subject of the formula
Example 2: Multiplication/division b = a·c
Whatever you do to one side, you must do to the other
side too
If you move a term from one side of the equals sign to the
other, we change the operation to do the opposite.
OR

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PRACTICE! In each case, make the letter given at the end, the subject of
the formula
d = v t v P = I2 R R y = mx + n x
A = P + I P d = m t + b b 𝑎2
+ 𝒃2
= 𝑐2 b
C = 2 π r r A =
1
2
b a b E = mc2 m
A = π r2 r P = 2l + 2w w V = π r2 h r
V =
1
3
π r2 h h A =
𝑎+𝒃
2
b m =
𝒚 𝟐
+ 𝑦1
𝑥2
+ 𝑥1
y2