A complex trinomial is of the form ax^2 + bx +c. To factorize the complex trinomial the steps are
Step1) multiply a (coefficient of leading term) and c (constant term)
Step2) List all factors of a*c
Step3) Find combinations of factors of a*c such that adding or subtrating these combinations would produce b.
Step 4) Write all four terms
Step5) Group and factor the binomials
Step6) Combine like terms
Example:
x^2 + 7x +10
Step1) 1 * 10 = 10
Step2) factors of 10 are 1,2,5,10
Step3) We get 2+5 =7
Step4) x^2 + 2x + 5x + 10
Step5) x(x+2) + 5(x+2)
Step6) (x+2)(x+5)