Question 43820
From 
(x+6)^2 - (x+9)^2
we recognize it is in the pattern 
a^2 - b^2 = (a + b)(a - b)
and so we can factor it like that
[(x+6)+(x+9)][(x+6)-(x+9)] =
(2x+15)(-3) = 
-6x - 45