Posted by anonymous on .
1. [12/(x^2  4)]  [(3x)/(x^2+2x)]
The answer is:
[(x^2 + 7x + 6)/x(x+z)(xz)
I don't understand how to get that! was the z a typo? even if it's supposed to be a 2  I don't understand!

math 
drwls,
yes, the z is a typo
Factor 1/(x+2) out of each term and see what you get.
[1/(x+2)][12/(x2)  (3x)/x]
=[1/(x+2)][12x/x(x2)  (3x)(x2)/x(x2)]
={1/[(x2)(x+2)]}[12x/x (3x)(x2)/x]
={1/[(x2)(x+2)]}[(x^2+ 7x +6)/x]
That is in the form of your answer (except for the typo "z" for 2), but it can be factored further.
= (x+6)(x+1)/[x(x2)(x+2)]