2 phần 5 + 6 phần 7 = ? . Giúp mik với
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Bài giải
\(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}=\frac{40}{60}+\frac{45}{60}+\frac{48}{60}=\frac{133}{60}\)
\(\frac{8}{5}+\frac{7}{6}+\frac{10}{9}+\frac{1}{2}=\frac{144}{90}+\frac{105}{90}+\frac{100}{90}+\frac{45}{90}=\frac{394}{90}\)
\(\frac{15}{17}-\frac{11}{13}+\frac{3}{26}=\frac{390}{442}+\frac{374}{442}+\frac{51}{442}=\frac{815}{442}\)
\(\frac{9}{12}\text{ x }\frac{4}{3}\text{ : }\frac{8}{5}=\frac{9}{12}\text{ x }\frac{4}{3}\text{ x }\frac{5}{8}=\frac{9\text{ x }4\text{ x }5}{12\text{ x }3\text{ x }8}=\frac{5}{8}\)
\(\frac{4}{5}\text{ x }\frac{15}{8}\text{ : }\frac{5}{7}=\frac{4}{5}\text{ x }\frac{15}{8}\text{ x }\frac{7}{5}=\frac{4\text{ x }15\text{ x }7}{5\text{ x }8\text{ x }5}=\frac{21}{10}\)
\(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}=\frac{40}{60}+\frac{45}{60}+\frac{48}{60}=\frac{133}{60}\)
\(\frac{8}{5}+\frac{7}{6}+\frac{10}{9}+\frac{1}{2}=\frac{144}{90}+\frac{105}{90}+\frac{100}{90}+\frac{45}{90}=\frac{197}{45}\)
\(\frac{15}{17}-\frac{11}{13}+\frac{1}{26}=\frac{390}{442}+\frac{374}{442}+\frac{51}{442}=\frac{815}{442}\)
\(\frac{9}{12}\times\frac{4}{3}:\frac{8}{5}=1:\frac{8}{5}=\frac{5}{8}\)
\(\frac{4}{5}\times\frac{15}{8}:\frac{5}{7}=\frac{3}{2}:\frac{5}{7}=\frac{21}{10}\)
a) \(\frac{3}{2}-\frac{5}{6}:x=\frac{5}{15}-\frac{3}{15}\)
\(\Leftrightarrow\frac{3}{2}-\frac{5}{6}:x=\frac{2}{15}\)
\(\Leftrightarrow\frac{5}{6}:x=\frac{3}{2}-\frac{2}{15}\)
\(\Leftrightarrow\frac{5}{6}:x=\frac{41}{30}\)
\(\Leftrightarrow x=\frac{5}{6}:\frac{41}{30}\)
\(\Leftrightarrow x=\frac{25}{41}\)
b) \(x-\frac{6}{7}.\frac{14}{8}=\frac{1}{2}-\frac{2}{5}\)
\(\Leftrightarrow x-\frac{3}{2}=\frac{1}{10}\)
\(\Leftrightarrow x=\frac{1}{10}+\frac{3}{2}\)
\(\Leftrightarrow x=\frac{8}{5}\)
c) \(x:\frac{6}{5}+\frac{2}{3}=\frac{7}{3}\)
\(\Leftrightarrow x:\frac{6}{5}=\frac{7}{3}-\frac{2}{3}\)
\(\Leftrightarrow x:\frac{6}{5}=\frac{5}{3}\)
\(\Leftrightarrow x=\frac{5}{3}.\frac{6}{5}\)
\(\Leftrightarrow x=2\)
TL
a)\(\frac{8}{7};\frac{7}{8}\)
Cách 1:\(\frac{8}{7}\) và \(\frac{7}{8}\) (MSC:56)
\(\frac{8}{7}=\frac{8x8}{7x8}=\frac{64}{56}\); \(\frac{7}{8}=\frac{7x7}{8x7}=\frac{49}{56}\)
Vì \(\frac{64}{56}>\frac{49}{56}\) nên \(\frac{8}{7}>\frac{7}{8}\)
Cách 2: Vì \(\frac{8}{7}>1;\frac{7}{8}< 1\) nên \(\frac{8}{7}>\frac{7}{8}\)
b)
Cách 1: \(\frac{9}{5};\frac{5}{8}\)(MSC:40)
\(\frac{9}{5}=\frac{9x8}{5x8}=\frac{72}{40};\frac{5}{8}=\frac{5x5}{8x5}=\frac{25}{40}\)
Vì \(\frac{72}{40}>\frac{25}{40}\)nên \(\frac{9}{5}>\frac{5}{8}\)
Cách 2: Vì \(\frac{9}{5}>1;\frac{5}{8}< 1\) nên \(\frac{9}{5}>\frac{5}{8}\)
HT
a: 5/7+5/4
=20/28+35/28=55/28
b: 3/2-4/6
=9/6-4/6=5/6
c: 5x3/4=15/4
d: 4/6:8=2/3x1/8=2/24=1/12
\(\frac{17}{33}.\frac{2}{5}+\frac{3}{5}.\frac{17}{33}-\frac{17}{33}\)
\(=\frac{17}{33}\times\frac{2}{5}+\frac{3}{5}\times\frac{17}{33}-\frac{17}{33}\times1\)
\(=\frac{17}{33}\times\left(\frac{2}{5}+\frac{3}{5}-1\right)\)
\(=\frac{17}{33}\times\left(1-1\right)\)
\(=\frac{17}{33}\times0=\frac{17}{33}\)
`B=-3-2/3+3/5(-10/9-25/3)-5/6`
`=-3-2/3-5/6+3/5(-10/9-50/9)`
`=-3-4/6-5/6+3/5*(-60)/9`
`=-3-9/6-4`
`=-7-3/2=-17/2`
Lời giải:
\(B=-3-\frac{2}{3}+\frac{3}{5}(\frac{-10}{9}-\frac{25}{3})-\frac{5}{6}\)
\(=-3-(\frac{2}{3}+\frac{5}{6})+\frac{3}{5}.(\frac{-10}{9}-\frac{75}{9})\)
\(=-3-\frac{4+5}{6}+\frac{3}{5}.\frac{-85}{9}=-3-\frac{9}{6}-\frac{17}{3}=-(3+\frac{9}{6}+\frac{34}{6})=\frac{-61}{6}\)
\(\dfrac{2}{5}+\dfrac{6}{7}=\dfrac{14}{35}+\dfrac{30}{35}=\dfrac{14+30}{35}=\dfrac{44}{35}\)
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