(2x+y)²-(x+2y)²要有详细过程

(2x+y)²-(x+2y)²要有详细过程
(2x+y)²-(x+2y)²要有详细过程

(2x+y)²-(x+2y)²要有详细过程
(2x+y)²-(x+2y)² 平方差
=[(2x+y)-(x+2y)][(2x+y)+(x+2y)]
=(2x+y-x-2y)(2x+y+x+2y)
=(x-y)(3x+3y)
=3(x-y)(x+y)
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(2x+y)²-(x+2y)²
=4x²+4xy+y²-（x²+4xy+4y²）
=4x²+4xy+y²-x²-4xy-4y²
=3x²-3y²