Question 205106
find the LCD of:
7/a^2+2a-63 , 8/a+9 
Before you can solve this you need to factorise,a^2+2a-63
when you factorise a^2+2a-63, you will get (a - 7)(a + 9)
So therefore taking both denominators thats (a + 9) and a^2+2a-63, the LCM is 
(a - 7)(a + 9)