(4) (a-b)3+(b-c)3 + (c-a) 3
888
=(a3-3a2b+3ab2-63) 09
+(63-362c+3bc2-c3)
+(c3-3c2a+3ca2-a³)
=-3a2b+3ab2-3b2c+3bc2-3c2a+3ca2
=-3(b-c)a2+3(62-c2)a-3(b2c-bc2)
=-3(b-c)a2+3(b+c)(b-c)a-3bc(b-c)
=-3(b-ca2-(b+c)a+bc)=xe
=-3(b-cxa-ba-c)
=3(a-b)(b-cc-a)
ee
x.001