第52页 - 江苏版启东中学作业本七年级数学（上下册）

A

C

4a+4

3

±36

$ \begin{aligned}解:原式&=(-1)²-(4a)² \\ &=1-16a². \\ \end{aligned}$

$ \begin{aligned} 解:原式&=(-2y^2)^2-(3x)^2 \\ &=4y^4-9x^2. \\ \end{aligned}$

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$解:原式=\frac{1}{9}a²-\frac{1}{4}b².$

解:原式=9x²-25a²b².

$ \begin{aligned} 解:原式&=3(x+2)(x-2) \\ &=3(x²-4) \\ &=3x²-12. \\ \end{aligned}$

$ \begin{aligned} 解:原式&=9y^2-25x^2-(16xy+4x^2-4y^2-xy) \\ &=9y^2-25x^2-15xy-4x^2+4y^2 \\ &=13y^2-29x^2-15xy \\ \end{aligned}$

$ \begin{aligned}解:原式&=(1+0.03)×(1-0.03) \\ &=1-0.03² \\ &=1-0.0009 \\ &=0.9991. \\ \end{aligned}$

$ \begin{aligned} 解:原式&=(100+\frac{1}{2})(100-\frac{1}{2}) \\ &=100^2-(\frac{1}{2})^2 \\ &=10000-\frac{1}{4} \\ &=9999\frac{3}{4}. \\ \end{aligned}$

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