第14页 - 启东中学作业本七年级数学人教版

$=-85×(25×4)$

$=-85×100$

$=-8500$

$=-8×\frac {4}{3}×\frac {5}{4}×\frac {5}{4}$

$=-\frac {50}{3}$

=0

$=\frac {7}{9}×36-\frac {5}{6}×36+\frac {3}{4}×36-\frac {7}{18}×36$

$=28-30+27-14$

$=11$

$=\frac {1}{6}×(-48)+\frac {3}{4}×48-\frac {1}{12}×48$

$=-8+36-4$

$=24$

$=5×7+5×(-6)$

$=5×(7-6)$

$=5$

$=(4-3+6)×(-3 \frac {6}{7})$

$=7×(-\frac {27}{7})$

$=-27$

$=(100-\frac {1}{25})×(-25)$

$=100×(-25)+\frac {1}{25}×25$

$=-2500+1$

$=-2499$

$=\frac {22}{17}×\frac {25}{8}×\frac {8}{15}×\frac {34}{9}$

$=\frac {220}{27}$

$=\frac {3}{2}×\frac {5}{4}×\frac {7}{6}×···×\frac {21}{20}×\frac {2}{3}×\frac {4}{5}×\frac {6}{7}×···×\frac {20}{21}$

$=(\frac {3}{2}×\frac {2}{3})×(\frac {5}{4}×\frac {4}{5})×(\frac {7}{6}×\frac {6}{7})×···×(\frac {21}{20}×\frac {20}{21})$

$=1×1×1×···×1$

$=1$