第45页 - 江苏版实验班提优训练数学七年级上下册答案

解：原式$=(-2023-\frac {2}{3})+(-2024-\frac {5}{6})+(4304-\frac {1}{2}) $

$=[(-2023)+(-20224)+43304]+[(-\frac {2}{3})+(-\frac {5}{6})-\frac {1}{2}]$

$=257+(-2)$

$=255$

解：原式$=-\frac {1}{1×2}-\frac {1}{2×3}-\frac {1}{3×4}-\frac {1}{4×5}-\frac {1}{5×6}- \frac {1}{6×7}$

$=-(1-\frac {1}{2})-(\frac {1}{2}- \frac {1}{3})-(\frac {1}{3} -\frac {1}{4})-(\frac {1}{4} -\frac {1}{5})-(\frac {1}{5}-\frac {1}{6})-(\frac {1}{6}-\frac {1}{7})$

$=-1+\frac {1}{7}$

$=-\frac {6}{7}$

解：原式$=(-\frac {6}{5})×(-\frac {2}{3}+\frac {17}{3})$

$=-\frac {6}{5}×5$

$=-6$

解：原式$=(\frac 38-\frac 16+\frac {5}{12})×(-24)$

$=\frac 38×(-24)-\frac 16×(-24)+\frac {5}{12}×(-24)$

$=-9+4-10$

$=-15$