Question 70673
9x^2+12xy+4y^2-25 You started on the right path factoring the x & y terms but 
didn't include the -25. 
Assume (3x+2y)=z then you have z^2-25=(z-5)(z+5) Thus we have:
(3x+2y)^2-25
(3x+2y)^2-5^2
(3x+2y-5)(3x+2y+5)