Question 430895
Step back a second and think back to the commutative rules.
Does a*b = b*a ??
You know it does.
So if a = (x-3) and b=(x+6)
does it matter which factor is listed first?
Nope

So your answer and the book's answer are mathematically equivalent.
Not sure where you found that order of factor matters. Order does not matter when mulitplying.

Here's a nice tool to help verify your factoring work --> http://72.3.253.76:8080/webMathematica3/quickmath/algebra/factor/basic.jsp