第1页 - 数学 - 电子课本网

B

C

B

$\frac{1}{2}$

$-2$

$\frac{1}{2}$

$7\times10^{-4}$

$(2n + 1)^2-(2n - 1)^2 = 8n$

$ \begin{aligned} 解：原式&=2-1-1+\frac {1}{2} \\ &=\frac {1}{2} \\ \end{aligned}$

$ \begin{aligned}解：原式&=\frac {1}{2}-(-8)+1 \\ &=9\frac {1}{2} \\ \end{aligned}$

$ \begin{aligned} 解：原式&=-1+6×\frac {\sqrt{3}}{2}-(2-\sqrt{3}) \\ &=-1+3\sqrt{3}-2+\sqrt{3} \\ &=4\sqrt{3}-3 \\ \end{aligned}$

$ \begin{aligned}解：原式&=-4-(\frac {1}{2}×24-\frac {1}{3}×24-\frac {5}{6}×24) \\ &=-4-(12-8-20) \\ &=-4-(-16) \\ &=12 \\ \end{aligned}$