Question 184437
X2-2XY-15Y2= 
(x + 3y)(x - 5y) 
---------------------
- 
5X2+25X+30
= 5(x^2 + 5x + 6)
=5(x+3)(x+2)
-------------------------
 
X2-XY-12Y2
= (x-4y)(x+3y)
------------------------
 
X2-7X+12
=(x-3)(x-4)

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Cheers,
Stan H.