Question

15．算一算．

$\frac{3}{7}$+$\frac{2}{7}$=	$\frac{5}{16}$-$\frac{1}{16}$=	$\frac{1}{5}$+$\frac{1}{5}$=	$\frac{9}{10}$-$\frac{4}{10}$=	$\frac{5}{6}$-$\frac{2}{6}$=
$\frac{2}{8}$+$\frac{6}{8}$=	1-$\frac{3}{8}$=	$\frac{1}{5}$+$\frac{4}{5}$=	$\frac{7}{9}$-$\frac{2}{9}$=	$\frac{1}{4}$+$\frac{2}{4}$=
$\frac{5}{12}$+$\frac{6}{12}$=	$\frac{5}{7}$-$\frac{4}{7}$=

Answer 1

分析 按照分?jǐn)?shù)加減法的計(jì)算方法計(jì)算．

解答 解：$\frac{3}{7}+\frac{2}{7}=\frac{5}{7}$     $\frac{5}{16}-\frac{1}{16}=\frac{1}{4}$       $\frac{1}{5}+\frac{1}{5}=\frac{2}{5}$        $\frac{9}{10}-\frac{4}{10}=\frac{1}{2}$       $\frac{5}{6}-\frac{2}{6}=\frac{1}{2}$
$\frac{2}{8}+\frac{6}{8}=1$         1-$\frac{3}{8}=\frac{5}{8}$           $\frac{1}{5}+\frac{4}{5}=1$         $\frac{7}{9}-\frac{2}{9}=\frac{5}{9}$         $\frac{1}{4}+\frac{2}{4}=\frac{3}{4}$
$\frac{5}{12}+\frac{6}{12}=\frac{11}{12}$       $\frac{5}{7}-\frac{4}{7}=\frac{1}{7}$

點(diǎn)評(píng) 口算題要看準(zhǔn)數(shù)和運(yùn)算符號(hào)，計(jì)算要認(rèn)真．