Factoring

As noted in previous examples, the signs on b and c give clues to determine which factors to use.

• If c is positive, then the factors must have the same sign.
  
  • If b is positive, then the factors are positive.
  • If b is negative, then the factors are negative.

• If c is negative, then the factors must have opposite signs; that is, one is negative and one is positive.
  
  • If b is positive, then the larger factor is positive.
  • If b is negative, then the larger factor is negative.