Question 363196
Factor the top and bottom and then reduce the fraction as needed.



4x^2 - 36 becomes (2x - 6)(2x + 6).



2x - 6 becomes 2(x - 3) and 2x + 6 becomes 2(x + 3).



The numerator becomes [4(x - 3)(x + 3)].



x^2 + 10x + 21 becomes [(x + 3)(x + 7)] = the denominator.



Our fraction now looks like this:



[4(x - 3)(x + 3)]/[(x + 3)(x + 7)]



What do you think we need to do now?



We need to cancel out common terms on the top and bottom.



I see that (x + 3) is found on the top and bottom.  So, we cancel out (x + 3) on the top and bottom.


The answer is:  4(x - 3)/(x + 7).


Done!