K³-g²k-gk²+g³=(k³+g³)-gk(g+k)=(g+k)(g²-gk+k²)-gk(g+k)=(g+k)(g²-gk+k²-gk)=
=(g+k)(g²-2gk+k²)=(g+k)(g-k)²
0,064-0,4z-z²+z³=(0,064+z³)-z(0,4+z)=(0,4+z)(0,16-0,4z+z²)-z(0,4+z)=(0,4+z)(0,16-0,4z+z²-z)=(0,4+z)(0,16-1,4z+z²)
1)(8a³-b³)/(4a²-b²)=(2a-b)(4a²+2ab+b²)/(2a+b)(2a-b)=(4a²+2ab+b²)/(2a+b)
2)(ab+ac)/(ab-3b+ac-3c)=a(b+c)/(b(a-3)+c(a-3))=
=a(b+c)/(a-3)(b+c)=a/(a-3)
поскольку 0,(8)≈0,9, то 0,9= 9/10.