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\(a,\dfrac{x}{4}=\dfrac{15}{20}\\ \Rightarrow\dfrac{x}{4}=\dfrac{3}{4}\\ \Rightarrow x=3\\ b,\dfrac{15}{x}=\dfrac{25}{35}\\ \Rightarrow\dfrac{15}{x}=\dfrac{5}{7}\\ \Rightarrow\dfrac{15}{x}=\dfrac{15}{21}\\ \Rightarrow x=21\\ c,\dfrac{x}{5}=\dfrac{26}{65}\\ \Rightarrow\dfrac{x}{5}=\dfrac{2}{5}\\ \Rightarrow x=2\\ d,\dfrac{3}{x}=\dfrac{51}{85}\\ \Rightarrow\dfrac{3}{x}=\dfrac{3}{5}\\ \Rightarrow x=5\)
a,x4=1520⇒x4=34⇒x=3b,15x=2535⇒15x=57⇒15x=1521⇒x=21c,x5=2665⇒x5=25⇒x=2d,3x=5185⇒3x=35⇒x=5
a) \(\dfrac{2}{3};\dfrac{5}{8};\dfrac{24}{25}\)
b) \(\dfrac{10}{15};\dfrac{12}{18};\dfrac{18}{27}\)
\(\dfrac{x}{5}=\dfrac{26}{65}\)
\(\dfrac{x}{5}=\dfrac{2}{5}\)
\(x=2\)
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\(\dfrac{3}{x}=\dfrac{51}{85}\)
\(\dfrac{3}{x}=\dfrac{3}{5}\)
`x=5`
( 12 x 13 + 14 x 15 + ... + 24 x 25 + 26 x 27 ) x ( 14 + 6 - 10 + 5 - 3 x 5 )
= ( 12 x 13 + 14 x 15 + ... + 24 x 25 + 26 x 27 ) x 0
= 0
\(\dfrac{x}{5}=\dfrac{26}{65}\)
\(\Leftrightarrow65x=130\)
\(\Leftrightarrow x=2\)
\(\dfrac{3}{x}=\dfrac{51}{85}\)
\(\Leftrightarrow51x=255\)
\(\Leftrightarrow x=5\)
`x/5=26/65`
`65xx x=5xx26`
`65xx x=130`
`x=130:65=2`
`3/x=51/85`
`51xx x=3xx85`
`51xx x=255`
`x=255:51=5`
một thửa ruộng hình vuông có chu vi là 100 mét.Người ta cấy lúa trung bình là 1 mét vuông thu hoạch được 12/25 kg.hỏi trên thửa ruộng đó người ta thu hoạch được bao nhiêu tạ thóc
a, 7/15 +4/5 =7/15+12/15 = 19/15
b,2/3-3/8=16/24-9/24=7/24
C,4/7x21/16:5/8=4/7x21/16x8/5=6/5
D,13x42x11/33x26x35=1/5
a: \(\dfrac{5}{3}\cdot\dfrac{7}{10}=\dfrac{5}{10}\cdot\dfrac{7}{3}=\dfrac{14}{3}>2\)
\(\dfrac{5}{7}:\dfrac{7}{10}=\dfrac{5}{7}\cdot\dfrac{10}{7}=\dfrac{50}{49}< 2\)
=>\(\dfrac{5}{3}\cdot\dfrac{7}{10}>\dfrac{5}{7}:\dfrac{7}{10}\)
b: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(\dfrac{8}{9}:\dfrac{4}{3}=\dfrac{8}{9}\cdot\dfrac{3}{4}=\dfrac{8}{4}\cdot\dfrac{3}{9}=\dfrac{2}{3}\)
Do đó: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{8}{9}:\dfrac{4}{3}\)
c: \(\dfrac{5}{11}\cdot\dfrac{33}{15}=\dfrac{5}{15}\cdot\dfrac{33}{11}=\dfrac{3}{3}=1\)
\(\dfrac{6}{17}\cdot\dfrac{34}{25}=\dfrac{34}{17}\cdot\dfrac{6}{25}=2\cdot\dfrac{6}{25}=\dfrac{12}{25}< 1\)
=>\(\dfrac{5}{11}\cdot\dfrac{33}{15}>\dfrac{6}{17}\cdot\dfrac{34}{25}\)
d: \(\dfrac{15}{19}\cdot\dfrac{38}{5}=\dfrac{15}{5}\cdot\dfrac{38}{19}=3\cdot2=6\)
\(\dfrac{15}{16}:\dfrac{3}{8}=\dfrac{15}{16}\cdot\dfrac{8}{3}=\dfrac{15}{3}\cdot\dfrac{8}{16}=\dfrac{5}{2}\)<6
=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)
a, \(\dfrac{5\times11\times15\times18}{6\times15\times22\times10}\)
= \(\dfrac{5\times11\times15\times6\times3}{6\times15\times11\times2\times2\times5}\)
= \(\dfrac{5\times11\times15\times6}{5\times11\times15\times6}\) \(\times\) \(\dfrac{3}{2\times2}\)
= 1 \(\times\) \(\dfrac{3}{4}\)
= \(\dfrac{3}{4}\)
b, \(\dfrac{7}{12}\) \(\times\) \(\dfrac{3}{5}\) + \(\dfrac{3}{5}\) \(\times\) \(\dfrac{5}{12}\)
= \(\dfrac{3}{5}\) \(\times\) ( \(\dfrac{7}{12}+\dfrac{5}{12}\))
= \(\dfrac{3}{5}\) \(\times\) \(\dfrac{12}{12}\)
= \(\dfrac{3}{5}\) \(\times\) 1
= \(\dfrac{3}{5}\)
\(a,\dfrac{x}{3}=\dfrac{10}{15}\\ \Rightarrow\dfrac{x}{3}=\dfrac{2}{3}\\ \Rightarrow x=2\\ b,\dfrac{x}{5}=\dfrac{26}{65}\\ \Rightarrow\dfrac{x}{5}=\dfrac{2}{5}\\ \Rightarrow x=2\)
a, \(\dfrac{x}{3}=\dfrac{10}{15}\Leftrightarrow\dfrac{5x}{15}=\dfrac{10}{15}\Rightarrow x=2\)
b, \(\dfrac{x}{5}=\dfrac{26}{65}\Leftrightarrow\dfrac{13x}{65}=\dfrac{26}{65}\Rightarrow x=2\)