x^2+12x+32. We're looking for factors of 32 that add up to 12. 32 can be broken down into pairs of factors as shown in the brackets: (1,32), (2,16), (4,8); if we add together the factors we get respectively: (33),(18),(12). So the last pair is what we want, (4,8). Now we can factorise: (x+4)(x+8).