2) 12p³-(1/3)p²-1-3p×(3/3)×p²=
=12p³-(1/3)p²-1-3p×1p²=
=12p³-(1/3)p²-1-3p³=9p³-(1/3)p²-1=
=(1/3)(27p³-p²-3)
4) 5x+(1/5)x-20+x+(17/20)-5x=
=(1/5)x-20+x+(17/20)=(6/5)x-(383/20)=
=1/20(24x-383)
6) 64-(2ab/(a-8)²)+2ab-(a²/(8-a)²)=
=64-(2ab/(a-8)²)+2ab-(a²/(-(a-8))²)=
64-(2ab/(a-8)²)+2ab-(a²/(a-8)²)=
64(a²-16a+64)-2ab+2a³b-32a²b+128ab
-a²/(a-8)²=
63a²-1024a+4096+126ab+2a³b-32a²b/(a-8)²
Больше никак не сократить!
8) x²+(6/x²)-9-(3(2x-1)/9)-x²=
=(6/x²)-9-((2x-1)/3)=
=(18-27x²-x²(2x-1))/3x²)=
=((18-27x²-2x³+x²)/3x²)=
=((-2x³-26x²+18)/3x²)
6+6+2=14 cм это периметр
периметр это сумма всех сторон