Now factor out the negative sign
Now we should take the term and factorise that, keeping in mind that it is not yet complete. (The and terms represent the constants)
Now we should see which constants give us a product of 12.
(1 x 12 ; 2 x 6 ; 3 x 4)
Now from those options we should find which also satisfies the middle term.
Can you take it from here? Just do it step by step.