Question

27a³+8b³-(3a+2b)(9a²+6ab+4b²) при а=–1 b=1.

Answer 1

(3a)^3+(2b)^3-(3a+2b)(9a^2+6ab+4b^2)=(3a+2b)(9a^2-6ab+4b^2) - (3a+2b)Х
(9a^2+6ab+4b^2)=(3a+2b)(9a^2-6ab+4b^2-9a^2-6ab-4b^2)=(3a+2b)x(-12ab)=(3x(-1)+2x1)x(-1)x1x(-12)=-12