Three and 8/9 plus 8/9 in simplest form

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

    choose the correct definition for  extremo.  a.  end      b.  extra      c.  extract      d.  eventual 

What is the domain of the given function? {(3,-2), (6, 1), (-1, 4), (5,9), (-4, 0); o {x | x= -4,-1, 3, 5, 6} o {yl y = -2,0, 1,4,9} o {x|x = -4,-2, -1,0, 1, 3, 4, 5, 6, 9} o y y = 4,-2, -1, 0, 1, 3, 4, 5, 6, 9}