2(7.3-1.6а)+3.2а-9.6=14.6-3.2а+3.2а-9.6=14.6-9.6=5
(5х-4m)(25x^2+20mx+16m^2)
18с²-2(3с-1)²=18с²-2(9с²-6с+1)=18с²-18с²+12с-2=12с-2
(a-5)²-16b²=(a-5)²-(4b)²=((a-5)+4b)((a-5)-4b)=(a-5+4b)(a-5-4b)
x²-y²-5x-5y=(x²-y²)+(-5x-5y)=(x+y)(x-y)-5(x+y)=(x+y)((x-y)-5)=(x+y)(x-y-5)
27-x⁹=3³-(x³)³=(3-x³)(3²+3x³+(x³)²)=(3-x³)(9+3x³+x⁶)