Question

计算 (-2ab) (3a²-2ab-4b²） （x-y-3）（x+y+3）

Answer 1

(-2ab) (3a²-2ab-4b²）

=-6a^3b+4a^2b^2+8ab^3

（x-y-3）（x+y+3）

=x^2-(y+3)^2

=x^2-y^2-6y-9

-2a²+0.5

=1/2*(1-4a^2)

=1/2*(1+2a)(1-2a)

已知x+y=3,xy=1,求x³y²+x²y³

x³y²+x²y³=x^2y^2(x+y)

=(1^2)*3

=3

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