1) variant
1. c2-3c-2c+1-c2= c+1
2.7x+56+x2-64= x2+7x-8
3.4x2+20x-4x2-20x+25= 25
1) y^3+21*y^2+147*y+343-y^3-21*y^2>0
147y+343>0
147y>-343
y>-2.(3)
2)216-54y+18y^2-y^3+y^3-18y^2<0
216-54y<0
54y>216
y>4
1) a^3+8
2) x^3+27
3) m^3-64
4) 8x^3-y^3
5) 27a^3-8b^3
6) 1+c^3
2^(5n+7):2^(3n-5)=2^(5n+7-3n+5)=2^(2n+12)=2^(2*(n+6))=4^(n+6)
Ответ: n+6