Question 836155
(ii) is the difference of squares.  {{{(3m+9n)(3m-9n)}}}


(i) Look for factors of 42 which could be arranged as sum or difference to give -1.  Obvious choice is 6 and 7, but which signs? For the -42, one be negative and other be positive.  For the -x, you want 6-7:
{{{(x+6)(x-7)}}}