Question

9．$\frac{5}{3}$×$\frac{2}{3}$÷2=$\frac{5}{3}$×$\frac{3}{2}$×$\frac{1}{2}$×．（判斷對(duì)錯(cuò)）

Answer 1

分析 $\frac{5}{3}$×$\frac{2}{3}$÷2先把除法變成乘法，再?gòu)淖蟮接矣?jì)算；$\frac{5}{3}$×$\frac{3}{2}$×$\frac{1}{2}$按照從左到右的順序計(jì)算，得出結(jié)果再比較．

解答 解：$\frac{5}{3}$×$\frac{2}{3}$÷2
=$\frac{5}{3}$×$\frac{2}{3}$×$\frac{1}{2}$
=$\frac{10}{9}$×$\frac{1}{2}$
=$\frac{5}{9}$

$\frac{5}{3}$×$\frac{3}{2}$×$\frac{1}{2}$
=$\frac{5}{2}$×$\frac{1}{2}$
=$\frac{5}{4}$
$\frac{5}{9}$＜$\frac{5}{4}$原題說(shuō)法錯(cuò)誤．
故答案為：×．

點(diǎn)評(píng) 解決本題關(guān)鍵是知道計(jì)算分?jǐn)?shù)除法的兩變：除號(hào)變乘號(hào)，除數(shù)變倒數(shù)；而計(jì)算乘法時(shí)不需要變化．