скорее так...
Сократите алгебраическую дробь
(m+2c)(m²-2mc+4c)
(m^3+8c^3)/(4c^2-2cm+m^2)=--------------------------- = (m+2c)
(4c^2-2cm+m^2)
(3x^2-y) (9x^4+3x^2y+y^2) (27x^6-y^3)/(9x^4+3x^2y+y^2)=-------------------------------------- = (3x^2-y)
(9x^4+3x^2y+y^2)