https://tex.z-dn.net/?f=4xy%2B12y-4x-12%3D%284xy-4x%29%2B%2812y-12%29%3D4x%28y-1%29%2B12%28y-1%29
1. 4(xy-3y-x-3)
2. 48+ab-30b
3. -a(b+5)•(c+4)
https://tex.z-dn.net/?f=4xy%2B12y-4x-12%3D%284xy-4x%29%2B%2812y-12%29%3D4x%28y-1%29%2B12%28y-1%29
1. 4(xy-3y-x-3)
2. 48+ab-30b
3. -a(b+5)•(c+4)