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

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：＞，＜，＜，=．

點評 此題考查了不用計算判斷因數與積之間大小關系的方法．