Candidates were expected to differentiate 3x2 + 2l + xy + x -7 = ° with respect to
                  .                     dy    dy                         .                  dy          6x+y+l                      dy
                                                      xtoobtam6x+4y-+y+x-+ 1 =O which gave -= . To find - at
                                        dx    dx                                             dx            4y+x                         dx
(-2, 1), candidates should substitute -2 for x and 1 for y and after simplifying,
would obtain dy = 5. These steps were reportedly followed by majority of the
                         dx                                                                     .
candidates except for the few who were not able to manipulate directed numbers correctly hence they lost some marks.