30.
31. 6,25х²-100=(2,5х-10)(2,5х+10)
32. (x+y)²-z²=(x+y+z)(x+y-z)
33. (a+b)²-(a-b)²=(a+b+a-b)(a+b-a+b)=2a*2b=4ab
34. (2p-m)²-(p+2m)²=(2p-m+p+2m)(2p-m-p-2m)=(3p-m)(p-3m)
35. (3a-2b)²-(4a+b)²=(3a-2b+4a+b)(3a-2b-4a-b)=(7a-b)(-a-3b)
36. 25z²-(2t+3z)²=(5z-2t-3z)(5z+2t+3z)