Question 3911
  Another question which is unclear, how high is the net (3 ft?)
  How hight about the players (hit & receive the ball on the ground)?
  It is your responsibility to post a clear question so that the reader
  can understand. Don't just expect for answers. 
  
   One possibleanswer is
  y = k(x-12)(x+12),
  when x = 0, y = 10, so 10 = -144 k, k = -5/72

  the equation is y = -5/72(x-12)(x+12),

  Kenny