(а³-b³)³-(a³+b³)³+6a6b³=-2b9

(a³-b³-a³-b³)*( (a³-b³)²+(a³-b³)(a³+b³)+(a³+b³)²) + 6a^6* b³=-2b^9 -2b³*(a^6-2a³b³+b^6+a^6-b^6+a^6+2a³b³+b^6) + 6a^6*b³ = -2b^9 -2b³*(3a^6+b^6) + 6a^6*b³= -2b^9 -6a^6 * b³ -2b^9 + 6a^6* b³= -2b^9 - 2b^9 = -2b^9