LEARN MATH STEP BY STEP THROUGH VERY EASY PROCESS

FRAMING OF FORMULAE

**Framing a Formula**

**Step.1) Choose literals (Variables), such as a, x, A, X for
the quantities you are working with, certain symbols are traditionally used to
denote certain variables. However, the same symbol may be used to denote
different variables in different contexts. for instance, ‘p’ is used to denote
power in physics and principal in mathematics. ‘A’ is used to denote area in
mensuration and amount in the context of interest.**

**Step.2) Use the rules or conditions relevant to the context
to establish the relation between the variable.**

**Step.3) The subject of a formula is written on the left-hand
side of the equality sign, while the other variables and constants are usually
written on the right-hand side of the equality sign in a formula.**

**Example.- If a man’s
age is just triple of his son and if the age of father implies by F and son’s
age is implies by S, then the relation between father & son’s age is F = 3S**

**When one quantity is expressed in terms of odd other
quantities, the quantity thus expressed is called the subject of the formula.**

**Area ‘A’ of the rectangle, of length ‘L’ and breadth ‘B’, is
A = L X B**

**In this formula, the area is expressed in terms of the other
variables, namely the length and breadth, so area is the subject of the
formula, but it may be necessary to express the length in terms of the area and
the breadth. To do so, we can transform the relations by dividing both sides by
‘B’. Then, in the transformed formula –**

** A**

** L =
-----------**

** B**

**The subject is L, transforming a formula this way is called
changing the subject of the formula. We
have already made use of such transformations.**

** If, I =
simple interest, P = principle , R = rate
, T = Time **

** P X
R X T**

** I = -----------------**

** 100**

**Given I and any two of the other variable, the third can be
worked out by changing the subject of the formula, for example –**

** I X 100 I X 100 I X 100**

** P = ------------- , R
= ------------- , T = -------------**

** R
X T P
X T P X R**