Linear or Quadratic

Question

Justify (provide a reasoning and math evidence) which equation(s) below represents are linear relation, quadratic relation or neither. 

y = -4 + 8x  

y = -4 + 8x2  

y = -4 + 8x4 

y = 8(x + 4)  

y = -4 + 8x   

y = (x – 8)(x + 4)

Answer 1

Linear equations are of the first degree.

Quadratic equations are of the second degree.