Verified Answer :

\(x^2+x-12\)
Answer:
\(=(x-3)(x+4)\)

1,12
2,6
3,4 
thats all 
since its -12 , one will be negative and one will be positive.
since there's 1X, the two numbers differ by 1 only 3 & 4 fit so it's 4+ and -3  
(X+4)*(X-3)