The domain of the rational terms:
Because division by zero isn't allowed, I have to find all values of x, that would cause division by zero. In other words, to find the domain, I have to solve for the zeros of denominator.

 

Caculate:


a) problem:
 
         =             
       2x
 
b) problem:
 
          4b                 =              
 (b - 7) * (2b + 5)
 
 
c) problem: 
 
      3        =              
  x - 7y

answers:


a) answer:

2x ≠ 0  / : 2 

x ≠ 0      

0 is not allowed as an answer in this rational term.

  

b) answer:

1. part of the denominator (b - 7):

b - 7 ≠ 0     / + 7           

b ≠ + 7    

2. part of the denominator (2b + 5):

2b + 5  ≠ 0    / - 5

2b ≠ - 5     / : 2

b  ≠ - 2,5    

- 7 and - 2,5 are not allowed as an answer in this rational term.

 

c) answer:

x - 7y ≠ 0    / + 7y

x  ≠ + 7y         

+ 7y is not allowed as an answer in this rational term.