1)Y8-1=(y4)2-1=(y4-1)(y4+1) = ((y2)2-1)(y4+1) = (y2-1)(y2+1) (y4+1) =(y-1)(y+1) (y2+1) (y4+1)
2)x4-z4=(x2)2-(z2)2= (x2-z2)(x2+z2)=(x-z)(x+z)(x2+z2)
на скриншоте лучше показано
