Above, we have a quadratic trinomial.
To factor a quadratic trinomial, first find two integers (m and n) which have a sum equal to b, and a product equal to c. Then, write the factors in the form (x + m)(x + n).
Here, we've found the factors of "9". 3 and 3 have a sum of 6, which is the coefficient of our second term.
Below is our factored trinomial: