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.