第35页 - 初中数学七年级下册新课程自主学习与测评答案

D

B

$=19×(-\frac {1}{7})-5×(-\frac {1}{7})$

$=(19-5)×(-\frac {1}{7})$

$=14×(-\frac {1}{7})$

$=-2$

$=\frac {1}{8}÷(-\frac {3}{8})×(-\frac {1}{3})$

$=\frac {1}{8}×\frac {8}{3}×\frac {1}{3}$

$=\frac {1}{9}$

有错误，应该按照从左到右的顺序计算

$-9÷\frac {3}{2}×\frac {2}{3}=-9×\frac {2}{3}×\frac {2}{3}=-6×\frac {2}{3}=-4$

$=\frac {2}{3}×\frac {8}{5}+(-\frac {1}{4})$

$=\frac {16}{15}-\frac {1}{4}$

$=\frac {49}{60}$

$=\frac {7}{4}÷\frac {3}{2}+\frac {13}{8}÷\frac {13}{16}$

$=\frac {7}{4}×\frac {2}{3}+\frac {13}{8}×\frac {16}{13}$

$=\frac {7}{6}+2$

$=3 \frac {1}{6}$