第108页 - 江苏版实验班提优训练数学八年级上下册答案

A

D

A

$x≥\frac{1}{2} $

5

$ \begin{aligned}解:原式&=x^{2} -(\sqrt {7} )^{2} \\ &=(x+\sqrt {7} )(x-\sqrt{7}) \\ \end{aligned}$

$ \begin{aligned}解:原式&=x(x^{2} -5) \\ &=x[x^{2} -(\sqrt {5} )^{2} )] \\ &=x(x+\sqrt {5} )(x-\sqrt{5}) \\ \end{aligned}$

$ \begin{aligned}解:原式&=(2x)^{2} -(\sqrt {11} )^{2} \\ &=(2x+ \sqrt{11})(2x-\sqrt{11}) \\ \end{aligned}$

$ \begin{aligned}解:原式&=x^{2} -2\sqrt {3} x+(\sqrt {3} )^{2} \\ &=(x-\sqrt{3})² \\ \end{aligned}$

D

C

A

0

x≥-1且x≠2

2

$ \begin{aligned}解:原式&=1+2+8+6 \\ &=17 \\ \end{aligned}$