Choose a language: English | Malayalam

Algebra (Intermediate) - Substitution and Formula
 
Substitution | Formula
 

Substitution

We can be given the number for the letter p = 4. This means we can replace p by 4 in an expression.

Therefore
p + 2  
 = 4 + 2 = 6
     
 
p – 1  
 = 4 – 1 = 3
     
 
3p  
 = 3 x 4 = 12
     
 
p  
 = 4 = 2
 
2  
    2

p3 = 4 x 4 x 4 = 64

We say that we have substituted 4 for p in the expression.

Example: Given t = 3 and m = 5, find the value of the following:

7t = 7 x 3 = 21

2t  + 4m = 2 x 3 + 4 x 5
  = 6 + 20
  = 26
   
5t2 = 5 x 3 squared
  = 5 x 9
  = 45
   
4m + 2t = 4 x 5 + 2 x 3
10
     10
  
   
  = 8

 

Formula

An example of a formula is P = 2L + 2W.

If we are given L = 5 and W = 7, we can work out the value of P by substituting into the formula as follows:

P = 2 x 5 + 2 x 7

P = 10 + 14

P = 24