【正文】
5 - 3 x 4 + ( m + 4) x 3 + ( n - 3 m ) x 2 + (4 m -3 n ) x + 4 n , ∵ 不含 x 3 和 x 2 項(xiàng): ∴????? m + 4 = 0n - 3 m = 0,解得:????? m =- 4n =- 12; (2) ∵ ( m + n )( m 2 - mn + n 2 ) = m 3 - m 2 n + mn 2 + m 2 n - m 2 n + n 3 = m 3 + n 3 ,當(dāng) m=- 4 , n =- 12 時(shí),原式= ( - 4) 3 + ( - 12) 3 =- 64 + ( - 172 8) =- 1 792. 。(34 x2 - 12 y2 ) - 6 xy a5+ (- 2a2)3; 解:原式= a2- 8a6=- 7a6; (2)[(a- b)3]2+ (a- b)a3 a2= a D . ( a3)2= a9 2 . 計(jì)算 (2 x3y )2的結(jié)果是 ( ) A . 4 x6y2 B . 8 x6y2 C . 4 x5y2