Question 879256
x^2 - x - 12 = 0
 (x - 4)(x + 3) = 0
 x = 4 or x = -3
What error did the other student make when solving? 
being absent when factoring was explained?? don't know...
Quadratics are solved by using {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}},
by factoring Or by completing the square