(a) Prove that for every integer x with 0 ≤ x ≤ 5, the seuqence consisting of {1,2,3,5,5,x} is not graphic. It is your job to put each particular value of x in the correct position in the sequence.
(b) If the sequence consisting of {x,7,7,5,5,4,3,2} is graphic, then what are all possible values for x? You may assume that 0 ≤ x ≤ 7. It is your job to put each particular value of x in the correct position in the sequence.