Aim: How do we solve quadratic equations by factoring?

When the product of two factors are equal to zero, at least one of the two factors must equal zero
Example:
   If 10(x+17)=0, then 10 or x+17 must be zero
     x+17=0
     x=-17
  If (x+9)(x-13)=0, then x+17 or x-13 must equal to zero
     x+9=0, x=-9
     x-13=0, x=13