3у²-27=3(у²-9)=3(у-3)(у+3)

3х²+12х+12=3(х²+4х+4)=3(х+2)²=3(x+2)(x+2)

у⁵-25у³=у³(у²-25)=у³(у-5)(у+5)

х²-4ху+4у²-25=(х-2у)²-5²=(х-2у-5)(х+2у+5)

а³-2а²+18-9а=а²(а-2)-9(а-2)=(а-2)(а²-9)=(а-2)(а+3)(а-3)

m²-6mn+9n²-m³+27n³=(m-3n)²+(27n³-m³)=(m-3n)²+(3n-m)(9n²+3mn+m²)=

(m-3n)²-(m-3n)(9n²+3mn+m²)=(m-3n)(m-3n+9n²+3mn+m²)