计算:(3m+3n)(3m-3n)-(3m+3n)^2+(3m-2n)^2

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计算:(3m+3n)(3m-3n)-(3m+3n)^2+(3m-2n)^2计算:(3m+3n)(3m-3n)-(3m+3n)^2+(3m-2n)^2计算:(3m+3n)(3m-3n)-(3m+3n)^

计算:(3m+3n)(3m-3n)-(3m+3n)^2+(3m-2n)^2
计算:(3m+3n)(3m-3n)-(3m+3n)^2+(3m-2n)^2

计算:(3m+3n)(3m-3n)-(3m+3n)^2+(3m-2n)^2
原式=(9m²-9n²)-(9m²+18mn+9n²)+(9m²-18mn+9n²)
=9m²-9n²-9m²-18mn-9n²+9m²-18mn+9n²
=-9m²-36mn-9n²