(a的3次方b的4次方-3a的2次方b的2次方+2a的2次方b的3次方)÷(-2分之1ab)的2次方
=(a^3b^4-3a^2b^2+2a^2b^3)÷(-ab/2)^2
=a^2b^2(ab-3+2b)÷(a^2b^2/4)
=4(ab-3+2b)
[9x的3次方y的2次方-2分之3(6x的3次方y的2次方+4xy)]÷(-3xy)
=[9x^3y^2-3/2(6x^3y^2+4xy)]÷(-3xy)
=[9x^3y^2-9x^3y^2-6xy)]÷(-3xy)
=(-6xy)÷(-3xy)
=2
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