If you have difficulty factoring trinomials with lead coefficient 1, then you can try the following approach. Some people call this the “bottoms up” method.  Note:  ALWAYS remember to factor out the GCF first (it will make all of the numbers smaller and easier to work with)

 

Given                                  Example:  

 

1.  Find  ac                                                       ac = =

 


2.  Find two factors of ac that                           since  ac =and  b=19,    we need to find two numbers whose product is       and that

     add up to b.                                                 add up to 19.      AND   .  So the numbers we want are 21 and – 2

 

 


3.  Divide each number by a                                                                  note:  in this problem  a was 6

     and reduce the fraction.                   

 


4.  Write two factors, bringing the                                                        

     bottoms up” to be the coefficients

     of the variable.                                        Answer:  

 

 

Remember, if you want to check to see if the trinomial is “factorable”, just check to

see if the discriminant () has a “nice” square root.  In our previous example…………

 

 =     and   so we KNOW that could be factored, it was just a case of figuring out HOW.

 

 

You try      ……………scroll down the page to see the steps.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ac = =

 

b=13        and 

 

Dividing each of   by 12 and reducing….

 

                                 

 

Now bring the “bottoms up” to write the factors….

 

Answer:   

 

Check: