The trinomial expression is .

The trinomial compare to general trinomial expression: , So a = 9, b = 12, c = 4.

To find two numbers with a sum of 12 and a product of .

This trinomial list of the factors of 36, and look for the pair of factors is a sum of 12.

Factors of 40	Sum of factor
\ 9, 4 \ 3, 12 \ \ \ 6, 6 \	\ 13 \ \ \ 15    \ 12 \

The correct factors are 6 and 6.

To factor trinomials of the form , find two integers, m and n, with a sum equal to b and a product equal to c.

Then write  .

Group terms with common factors.

Combine like terms using distributive property: ac  bc = (a b)c.

Check:

To check the solution by multiply the two factors.

    (Using FOIL method)

Product of two different sings is negative.

Product of two same sings is positive.

Combine like terms using distributive property: ac  bc = (a b)c.

The solution is "true".

The solution is .