When a trinomial is factored as (x+a)(x+b), what is the product of a and b?

Question

What is the product of a and b when it as (x+a)(x+b)?

Answer 1

The value of the function when x=0 is called the y-intercept.  It is the place where the function crosses the y-axis.  This is the point (0,ab).

 

Put x=0 into the expression and get ab.

 

Now, the "solutions" of (x=-a) and (x=-b) result from the Multiplicative Property of Zero (if the product is zero, then at least one of the factors must be 0).