1. c²d²-m²=(cd)²-m²=(cd-m)·(cd+m)
2. a²x²-0/25y=a²x²-1/4y²=(ax-1/2)·(ax+1/2)
3. 16y²z²-9a²n²=4²y²z²-3²a²n²=(4yz)²-(3an)²=(4yz-3an)·(4yz+3an)
4. x²y²-0,25p²q²=x²y²-1/4p²q²=(xy-1/2pq)·(xy+1/2pq)
