Most candidates performed poorly in this question. They were expected to obtain 2 equations in p and q by substituting the values x  =  ± 1 in the polynomial and then equate to the values of 2x + 1 when x  =  + 1.  The 2 equations are p + q = 5 and p-q = 1.  On solving simultaneously, p = 3 and q = 2.