(3x+2y)(3x-2y)-(3x-2y)^2+(3x+2y)^2 ,化简.当x=1/3,y=1/2时,求原式的值.

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(3x+2y)(3x-2y)-(3x-2y)^2+(3x+2y)^2 ,化简.当x=1/3,y=1/2时,求原式的值.
(3x+2y)(3x-2y)-(3x-2y)^2+(3x+2y)^2 ,化简.当x=1/3,y=1/2时,求原式的值.

(3x+2y)(3x-2y)-(3x-2y)^2+(3x+2y)^2 ,化简.当x=1/3,y=1/2时,求原式的值.
设a=（3x+2y),b=(3x-2y)
ab-b^2+a^2
=a^2-b^2+2ab-ab
=(a-b)^2-ab
=(3x+2y-(3x-2y))^2-(9x^2-4y^2)
=16y^2-9x^2+4y^2
=20y^2-9x^2
剩下的不用我说了吧

(3x+2y)(3x-2y)-(3x-2y)^2+(3x+2y)^2
=9x^2-4y^2+(3x+2y)^2-(3x-2y)^2
=9x^2-4y^2+24xy
=1-1+24/6=4

(3x+2y)(3x-2y)-(3x-2y)^2+(3x+2y)^2
=9x^2-4y^2-(9x^2-12xy+4y^2)+(9x^2+12xy+4y^2)
=9x^2-4y^2-9x^2+12xy-4y^2+9x^2+12xy+4y^2
=24xy-4y^2+9x^2
因为 9x^2=1 4y^2=1
所以原式=24*1/3*1/2=4
其实，我觉得这道题不化简，更容易做

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