Question 799080
factors (integers) a and b
a+b=-1 (1)
a*b=-12 (2)
rearrange (1) a=-(1+b)
subst for a in (2):
-(1+b)*b=-12
{{{ -b-b^2 = -12 }}}
rearrange  {{{b^2+b-12=0 }}}
solves for {{{ (-1 +-sqrt(1+4*12))/2 }}}
{{{ (-1 +- 7)/2 = 3 or -4}}}
Factors are 3 and -4