Question

12．在○里填上“＞”、“＜”或“=”．
$\frac{5}{12}$○$\frac{5}{12}$×$\frac{2}{5}$
$\frac{3}{5}$×$\frac{7}{4}$○$\frac{7}{4}$
$\frac{3}{4}$×$\frac{1}{5}$○$\frac{3}{4}$×5
$\frac{5}{6}$×$\frac{6}{5}$○$\frac{17}{8}$×$\frac{8}{17}$．

Answer 1

分析 一個數(shù)（0除外）乘小于1的數(shù)，積小于這個數(shù)；一個數(shù)（0除外）乘大于1的數(shù)，積大于這個數(shù)；據(jù)此解答．

解答 解：$\frac{5}{12}$＞$\frac{5}{12}$×$\frac{2}{5}$
$\frac{3}{5}$×$\frac{7}{4}$＜$\frac{7}{4}$
$\frac{3}{4}$×$\frac{1}{5}$＜$\frac{3}{4}$×5
$\frac{5}{6}$×$\frac{6}{5}$=$\frac{17}{8}$×$\frac{8}{17}$．
故答案為：＞，＜，＜，=．

點(diǎn)評 此題考查了不用計(jì)算判斷因數(shù)與積之間大小關(guān)系的方法．