Giải thích các bước giải:
Bài 4:
$\frac{1}{2}$+$\frac{2}{3}$=$\frac{1x3}{2x3}$ +$\frac{2x2}{2x3}$ =$\frac{3}{6}$ +$\frac{4}{6}$ =$\frac{3+4}{6}$ =$\frac{7}{6}$ ;
$\frac{5}{8}$-$\frac{1}{4}$ =$\frac{5}{8}$ -$\frac{1x2}{4x2}$ =$\frac{5}{8}$ -$\frac{2}{8}$ =$\frac{5-2}{8}$ =$\frac{3}{8}$ ;
$\frac{1}{6}$+$\frac{3}{4}$ +$\frac{1}{8}$ =$\frac{1x4}{6x4}$+$\frac{3x6}{4x6}$ +$\frac{1x3}{8x3}$ =$\frac{4}{24}$ +$\frac{18}{24}$ +$\frac{3}{24}$ =$\frac{4+18+3}{24}$ =$\frac{25}{24}$ ;
5-$\frac{4}{9}$ =$\frac{5}{1}$ -$\frac{4}{9}$ =$\frac{5x9}{1x9}$ -$\frac{4}{9}$ =$\frac{45}{9}$ -$\frac{4}{9}$ =$\frac{45-4}{9}$ =$\frac{41}{9}$
Bài 5: Tìm X
X+$\frac{5}{9}$ =$\frac{4}{3}$
X= $\frac{4}{3}$ -$\frac{5}{9}$
X= $\frac{4x3}{3x3}$ -$\frac{5}{9}$
X= $\frac{12}{9}$ -$\frac{5}{9}$
X= $\frac{12-5}{9}$
X= $\frac{7}{9}$
X-$\frac{4}{9}$ =$\frac{1}{2}$
X= $\frac{1}{2}$ +$\frac{4}{9}$
X= $\frac{1x9}{2x9}$ +$\frac{4x2}{9x2}$
X= $\frac{9}{19}$ +$\frac{8}{19}$
X= $\frac{9+8}{18}$
X= $\frac{17}{18}$
$\frac{6}{13}$ +X=$\frac{7}{6}$
X= $\frac{7}{6}$ -$\frac{6}{13}$
X= $\frac{7x13}{6x13}$ -$\frac{6x6}{13x6}$
X= $\frac{91}{78}$ -$\frac{36}{78}$
X= $\frac{91-36}{78}$
X= $\frac{55}{78}$
$\frac{13}{5}$ -X= $\frac{5}{6}$
X= $\frac{13}{5}$ -$\frac{5}{6}$
X= $\frac{13x6}{5x6}$ -$\frac{5x5}{6x5}$
X= $\frac{78}{30}$ -$\frac{25}{30}$
X= $\frac{78-25}{30}$
X= $\frac{43}{30}$
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