There are several characteristics that define a linear function: 
 
 1) They are of the form 
 , where m and b are real constants, or they can also have the form
, where m and b are real constants, or they can also have the form 
 if the function is of several variables. Where a, b, c are real numbers.
 if the function is of several variables. Where a, b, c are real numbers. 
 2) The degree of the variable x is always equal to 1 or 0. That is, if there is an expression of the form 
 or
 or 
 , the function is not linear.
, the function is not linear. 
 3) Your domain is all real numbers 
 4) The graph of its function in the xy plane is always a straight line. 
 
 Analyzing the aforementioned equation: 
 The function 
 does not have the form described, since it has a multiplication of two variables (
 does not have the form described, since it has a multiplication of two variables (
 ).
). 
 The graph of its function in the xy plane is a hyperbola 
 Your domain is not all real numbers, because the function is not defined for 
