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10. 若$A = x^{2}-3x - 6,B = 2x^{2}-4x + 6$,则$3A - 2B=$
$-x^{2}-x - 30$
.
答案：
10.$-x^{2}-x - 30$
11. (本题8分)计算:
(1) $(3x^{2}+4 - 5x^{3})-(x^{3}-3 + 3x^{2})$;
(2) $2(2xy^{2}-\frac{1}{2}y^{2})-(4xy^{2}+\frac{2}{3}y^{2}-x^{2}y)-\frac{4}{3}y^{2}$,其中$x = \frac{3}{2},y = -\frac{1}{3}$.
(1) $(3x^{2}+4 - 5x^{3})-(x^{3}-3 + 3x^{2})$;
(2) $2(2xy^{2}-\frac{1}{2}y^{2})-(4xy^{2}+\frac{2}{3}y^{2}-x^{2}y)-\frac{4}{3}y^{2}$,其中$x = \frac{3}{2},y = -\frac{1}{3}$.
答案：
11.
(1)$7 - 6x^{3}$
(2)$-3y^{2}+x^{2}y$,$-\frac{13}{12}$
(1)$7 - 6x^{3}$
(2)$-3y^{2}+x^{2}y$,$-\frac{13}{12}$
12. (本题6分)已知$(a - 3)x^{2}y^{|a|}+(b + 2)$是关于$x,y$的五次单项式,求$a^{2}-3ab + b^{2}$的值.
答案：
12.$-5$
13. (本题6分)化简求值:
$3x^{2}+2xy - 4y^{2}-2(3xy - y^{2}-2x^{2})$,其中$x = 1,y = -2$.
$3x^{2}+2xy - 4y^{2}-2(3xy - y^{2}-2x^{2})$,其中$x = 1,y = -2$.
答案：
13.7
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