(3m-2n)(9m方+6mn+4n方)-(3m+2n)(9m方-6mn+4n方)计算要过程拜托各位了 3Q

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(3m-2n)(9m方+6mn+4n方)-(3m+2n)(9m方-6mn+4n方)计算要过程拜托各位了 3Q
(3m-2n)(9m方+6mn+4n方)-(3m+2n)(9m方-6mn+4n方)计算要过程拜托各位了 3Q

(3m-2n)(9m方+6mn+4n方)-(3m+2n)(9m方-6mn+4n方)计算要过程拜托各位了 3Q
立方和公式a^3+b^3=(a+b)(a^2-ab+b^2) 立方差公式a^3-b^3=(a-b)(a^2+ab+b^2) a^2表示a的平方;a^3表示a的立方 (3m-2n)(9m^2+6mn+4n^2)-(3m+2n)(9m^2-6mn+4n^2) =(3m-2n)((3m)^2+3m*2n+(2n)^2)-(3m+2n)((3m)^2-3m*2n+(2n)^2) =((3m)^3-(2n)^3)-((3m)^3+(2n)^3) =(3m)^3-(2n)^3-(3m)^3-(2n)^3 =-2(2n)^3 =-16n^3