第43页 - 江苏版启东中学作业本七年级数学（上下册）

1

5

$-\frac {1}{3}$

$=-5+8÷4+\frac {1}{8}×(-16)+\frac {1}{4}×(-16)-\frac {1}{2}×(-16)$

$=-5+2-2-4+8$

$=-1$

$=(100-\frac {1}{17})×(-17)$

$=100×(-17)- \frac {1}{17}×(-17)$

$=-1700+1$

$=-1699$

$=-|8×(-8)|-(\frac {1}{16}×16)^3$

$=-64-1$

$= -65$

$=(\frac {3}{5}-\frac {1}{2}-\frac {7}{12})×60× (\frac {1}{7}-\frac {3}{7}-\frac {5}{7})$

$= (\frac {3}{5}-\frac {1}{2}-\frac {7}{12})×(-60)$

$=\frac {3}{5}×(-60)-\frac {1}{2}×(-60)-\frac {7}{12}×(-60)$

$=-36+30+35$

$=29$

16

$ 解：(2)∵2△3=2×2=4$

$∴(2△3)△(-5)=4△(-5)=(-5)^2=25$

$\frac {1}{n}-\frac {1}{n+1}$

$\frac {2021}{2022}$

$解：(3) 原式 = \frac {1}{2} × (\frac {1}{2}-\frac {1}{4}+\frac {1}{4}-\frac {1}{6}+\frac {1}{6}- \frac {1}{8}+···+\frac {1}{2022}-\frac {1}{2024})$

$=\frac {1}{2} × (\frac {1}{2}-\frac {1}{2024})$

$=\frac {1}{2} ×\frac {1011}{2024}$

$=\frac {1011}{4048}$