Just a difference of squares
Let (x + y + z) = a
Let (m -3) = b
So....we have
a^2 - b^2 = ( a + b) ( a - b)
Sub back in for a, b
(a + b) ( a - b) =
( x + y + z + m - 3) ( x + y + z - (m - 3) ) =
( x + y + z + m -3 ) (x + y + z - m + 3)
And that's it !!!!
