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第72頁(yè)

信息發(fā)布者：

?$1?(\frac 14+\frac 23)=\frac {1}{12}$?

?$\frac {1}{3}+\frac {2}{3}+\frac 16=1\frac {1}{6}($?小時(shí)?$)$?

答：最后?$\frac {1}{6}$?小時(shí)行了全程的?$\frac {1}{12}，$?行完全程一共用了

?$1\frac {1}{6}$?小時(shí)。

?$\frac {11}{12}-\frac {1}{3}-\frac {1}{3}=\frac {1}{4}$?

答：正確結(jié)果為?$\frac 14。$?

?$\frac {3}{5}+\frac {1}{10}=\frac {7}{10}($?升?$)$?

?$\frac {7}{10}+\frac {7}{10}=\frac {7}{5}($?升?$)$?

答：這瓶果汁原來有?$\frac 75$?升。

?$\frac {3}{5}?\frac {1}{10}=\frac {1}{2}($?升?$)$?

?$\frac {1}{2}+\frac {1}{2}=1($?升?$)$?

答：這瓶果汁原來有?$1$?升。

和

1

b

1

a

? $\frac {3}{1×2}-\frac 5{2×3}+\frac {7}{3×4}-\frac {9}{4×5}+\frac {11}{5×6}-\frac {13}{6×7}+\frac {15}{7×8}$?

?$=\frac {1+2}{1×2}-\frac {2+3}{2×3}+\frac {3+4}{3×4}-\frac {4+5}{4×5}+\frac {5+6}{5×6}-\frac {6+7}{6×7}+\frac {7+8}{7×8}$?

?$=(1+\frac {1}{2})?(\frac {1}{2}+\frac 13)+(\frac {1}{3}+\frac 14)?(\frac {1}{4}+\frac {1}{5})+...+(\frac {1}{7}+\frac 18)$?

?$=1+\frac {1}{2}?\frac 12-\frac 13+\frac 13+\frac {1}{4}-\frac 14-\frac 15+...+\frac 17+\frac 18$?

?$=1+\frac {1}{8}$?

?$=1\frac {1}{8}$?

?$\frac {5}{4}+\frac {5}{4}?\frac {12}{5}=\frac {1}{10}($?米?$) $?

答：?$a$?與?$b$?之間有?$\frac {1}{10}$?米。

?$\frac {4}{5}+\frac 34+\frac {1}{20}?1=\frac {3}{5} $?

答：這個(gè)班既喜歡語(yǔ)文又喜歡數(shù)學(xué)的學(xué)生占全班

人數(shù)的?$\frac 35。$?

?$1-(\frac {2}{3}+\frac {1}{6})=\frac {1}{6}$?

把?$\frac {1}{6}$?拆成兩個(gè)單位分?jǐn)?shù)之和

?$\frac {1}{6}=\frac {1}{9}+\frac {1}{18}$?

所以要去掉的單位分?jǐn)?shù)是?$\frac {1}{12}$?和?$\frac {1}{15}$?

答：要去掉?$\frac {1}{12}$?和?$\frac {1}{15}，$?才能使余下的分?jǐn)?shù)之和為?$1。$?

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