第75页 - 经纶学典学霸五年级数学上下册【江苏国标】

$=2+(\frac {9}{14}-\frac {3}{14})$

$=2+\frac 37$

$=2\frac {3}{7}$

$=\frac {3}{5}-\frac {1}{4}$

$=\frac {7}{20}$

$=\frac {19}{20}-\frac {9}{20}-\frac {2}{7}$

$=\frac {1}{2}-\frac {2}{7}$

$=\frac {3}{14}$

$=(\frac {1}{6}+\frac {5}{6})+(\frac {7}{8}-\frac {1}{8})$

$=1+\frac {3}{4}$

$=1\frac {3}{4}$

$=(\frac {5}{7}+\frac {2}{7})-(\frac {11}{13}+\frac {2}{13})$

$=1-1$

$=0$

$=(999\frac 89+\frac 19)+(99\frac 89+\frac 19)+$

$(9\frac 89+\frac 19)$

$=1000+100+10$

$=1110$

$=4×5+(\frac {1}{10}+\frac {11}{100}+\frac {111}{1000}+\frac {1111}{10000}+\frac {11111}{100000})$

$=20+(0.1+0.11+0.111+0.1111+0.11111)$

$=20.54321$

$1-\frac {3}{5}-\frac {8}{25}=\frac {2}{25}$

答：还剩下总票数的$\frac {2}{25}。$

$\frac {12}{5}-\frac {1}{3}=\frac {31}{15}($米$)$

$\frac {12}{5}+\frac {12}{5}+\frac {31}{15}+\frac {31}{15}=\frac {134}{15}($米$)$

答：这块桌布的周长是$\frac {134}{15}$米。

$\frac {4}{7}+\frac {5}{9}-1=\frac {8}{63}$

答：这时两车的距离占全程的$\frac {8}{63}。$

$\frac {13}{60}$

$\frac {1}{6}$

$\frac {14}{3}+\frac {35}{6}+\frac {15}{2}−15=3($千克$)$

$3÷3=1($千克$) $

答：一个空木箱有$1$千克重。

$=\frac {1}{1×2}+\frac {3−1}{1×2×3}+\frac {4−1}{1×2×3×4}+\frac {5−1}{1×2×3×4×5}+$

$ \frac {6−1}{1×2×3×4×5×6}+\frac {7-1}{1×2×3×4×5×6×7}$

$=\frac {1}{1×2}+\frac {1}{1×2}−\frac {1}{1×2×3}+\frac {1}{1×2×3}-\frac {1}{1×2×3×4}+$

$…+ \frac {1}{1×2×3×4×5×6}-\frac {1}{1×2×3×4×5×6×7}$

$=\frac {1}{1×2}+\frac {1}{1×2}- \frac {1}{1×2×3×4×5×6×7}$

$=1-\frac {1}{5040}$

$=\frac {5039}{5040} $