Answer:

Step-by-step explanation:
Quadratic function-
It is a function that can be represented by an equation of the form  , where
, where  
 
In a quadratic function, the greatest power of the variable is 2.
As in the first option the highest power is 3, so it is not a quadratic function.
Even though the power of x is 2 in the third option, but as it is in the denominator, so the overall power of x becomes -2. Hence it is not a quadratic function.
As the coefficient of  is 0 in case of fourth option, so it is not a quadratic function.
 is 0 in case of fourth option, so it is not a quadratic function.
Equation in option 2 satisfies all the conditions of quadratic function, hence it is the quadratic function.
 
        
                    
             
        
        
        
Answer:
21
Step-by-step explanation:
14+7=21
 
        
                    
             
        
        
        
Answer:
(C)
Step-by-step explanation:
AD and BC are parallel to each other. They are the same distance but they never touch.  
Your best answer would be C. 
Brainilest appreciated.