第47页 - 亮点给力提优课时作业本七年级数学江苏版

C

D

$-4$

$0$

$ \begin{aligned}解：原式&=-1-(－3×\frac{4}{9}－\frac{4}{3}×\frac{1}{4}) \\ &=-1- (－\frac{4}{3}－\frac{1}{3}) \\ &=-1+\frac{5}{3} \\ &=\frac{2}{3} \\ \end{aligned}$

$ \begin{aligned}解：原式&=-25×\frac{4}{15}+\frac{3}{4}×(\frac{16}{9}-8) \\ &=-\frac{20}{3}+ \frac{3}{4}×\frac{16}{9}－\frac{3}{4}×8 \\ &=-\frac{20}{3}+\frac{4}{3}-6 \\ &=-\frac{34}{3} \\ \end{aligned}$

$ \begin{aligned}解：原式&=(1000-1)×(－15) \\ &=1000×(-15)+(-1)×(-15) \\ &=-15000+15 \\ &=-14985 \\ \end{aligned}$

$ \begin{aligned} 解：原式&=999×[118\frac {4}{5}+(－\frac {1}{5})－18\frac {3}{5}] \\ &=999×100 \\ &=99900 \\ \end{aligned}$

6