第56页 - 经纶学典学霸七年级数学上下册【江苏国标】

B

1-y²

3m²-4mn-4n²

$-\frac{1}{2} $

0或1

$ \begin{aligned}解：原式&=2x²+6x-x-3 \\ &=2x²+5x-3 \\ \end{aligned}$

$ \begin{aligned}解：原式&=4m²-10m-10m+25 \\ &=4m²-20m+25 \\ \end{aligned}$

$ \begin{aligned}解：原式&=-12xy^2+16x^2-9y^4+12xy^2 \\ &=16x^2-9y^4. \\ \end{aligned}$

$ \begin{aligned} 解：原式&=3x^{2m}-6x^my^n+x^my^n-2y^{2n} \\ &=3x^{2m}-5x^my^n-2y^{2n} \\ \end{aligned}$

$ \begin{aligned}解：原式&=a²-2ab+3a-2ab+4b²-6b+2a-4b+6 \\ &=a²-4ab+4b²+5a-10b+6. \\ \end{aligned}$

$ \begin{aligned}解：原式&=(4a²+9a+2)-(2a²-a-1) \\ &=2a²+10a+3. \\ \end{aligned}$

D

-3

9

180

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