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a) $\frac{{14}}{{18}}:\frac{8}{9} = \frac{7}{9}:\frac{8}{9} = \frac{7}{9} \times \frac{9}{8} = \frac{{63}}{{72}} = \frac{7}{8}$
b) $\frac{9}{6}:\frac{3}{{10}} = \frac{3}{2}:\frac{3}{{10}} = \frac{3}{2} \times \frac{{10}}{3} = \frac{{30}}{6} = 5$
c) $\frac{4}{5}:\frac{{10}}{{15}} = \frac{4}{5}:\frac{2}{3} = \frac{4}{5} \times \frac{3}{2} = \frac{{12}}{{10}} = \frac{6}{5}$
d) $\frac{1}{6}:\frac{{21}}{9} = \frac{1}{6}:\frac{7}{3} = \frac{1}{6} \times \frac{3}{7} = \frac{3}{{42}} = \frac{1}{{14}}$
1
a) X=3/5 : 4/5
X=3/4
b) x=2/3 x 2/5
X=4/15
c) x=14/5 : 6/7
X=49/15
d) x=4/9 x 2/3
X= 8/27
2
7/15 < x < 4/3
7/15 < x < 20/15
X = 8/15;9/15;10/15;11/15;12/15;13/15;14/15;15/15;16/15;17/15;18/15;19/15
3
Hai năm nữa tuổi mẹ là
24:(4-1)x4 = 32 (tuổi)
Hai năm nữa tuổi con là
32:4=8 (tuổi)
Năm nay tuổi mẹ là
32-2=30 (tuổi)
Năm nay tuổi con là
8-2=6 (tuổi)
Đáp số tự ghi nhé
4/ 15 : 4 / 7 < x < 2 / 5 x 10 / 3
7 / 15 < x < 4 / 3
7 / 15 < x < 20 / 15
=> x có thể từ 8 / 15 đến 19 / 15
M = (345 x (6789 + 3456 - 245)/690) x 99/100 x 98/99 x...x 2/3 x 1/2
M = ((345 x 10000)/690) x 99/2 (rút gọn)
M = (10000/2) x 99/2
M = 5000 x 99/2
M = 247500
Ok nha
\(1-\left(\frac{12}{5}+y=\frac{8}{9}\right):\frac{16}{9}=0\)
\(1-\left(\frac{12}{5}+y-\frac{8}{9}\right)=0\times\frac{16}{9}\)
\(1-\left(\frac{12}{5}+y-\frac{8}{9}\right)=0\)
\(\frac{12}{5}+y-\frac{8}{9}=1-0\)
\(\frac{12}{5}-y+\frac{8}{9}=1\)
\(\frac{12}{5}-y=1-\frac{8}{9}\)
\(\frac{12}{5}-y=\frac{1}{9}\)
\(y=\frac{12}{5}-\frac{1}{9}\)
\(y=\frac{108}{45}-\frac{5}{45}\)
\(y=\frac{103}{45}\)
\(\frac{4}{15}:\frac{4}{7}< x< \frac{2}{5}.\frac{10}{3}\Leftrightarrow\frac{7}{15}< x< \frac{20}{15}\)
\(\Rightarrow x\in\left(8;9;10;11;12;13;14;15;16;17;18;19\right)\)
Ta có : \(\frac{4}{15}:\frac{4}{7}< x< \frac{2}{5}\cdot\frac{10}{3}\)
\(\Rightarrow\frac{4}{15}\cdot\frac{7}{4}< x< \frac{2}{5}\cdot\frac{10}{3}\)
\(\Rightarrow\frac{7}{15}< x< \frac{20}{15}\)
\(\Rightarrow7< x< 20\)
\(\Rightarrow x\in\left\{8;9;10;11;12;...;19\right\}\)
\(\frac{1}{2}+\frac{2}{3}< x< 4-\frac{4}{5}\)
\(\frac{7}{3}< x< \frac{16}{5}\)
\(\frac{35}{15}< x< \frac{48}{15}\)
=> x thuộc \(\left\{\frac{36}{15};\frac{37}{15};...;\frac{47}{15}\right\}\)
1) \(\frac{4}{5}.\frac{8}{3}.\frac{x}{7}=\frac{96}{105}\)
\(\frac{32.x}{105}=\frac{96}{105}\)
\(32x=96\)
\(x=3\)
Bài 1: Tìm \(x\)
\(\frac45\times\frac83\times\) \(\frac{x}{7}\) = \(\frac{96}{105}\)
\(\frac{32}{15}\) x \(\frac{x}{7}\) = \(\frac{32}{35}\)
\(\frac{x}{7}\) = \(\frac{32}{35}\) : \(\frac{32}{15}\)
\(\frac{x}{7}\) = \(\frac{32}{35}\) x \(\frac{15}{32}\)
\(\frac{x}{7}\) = \(\frac37\)
\(x=\frac37\times7\)
\(x=3\)
b; \(\frac74\times\frac{3}{x}\times\) \(\frac{11}{5}\) = \(\frac{231}{200}\)
\(\frac74\) x \(\frac{3}{x}\) = \(\frac{231}{200}\) : \(\frac{11}{5}\)
\(\frac74\times\frac{3}{x}\) = \(\frac{231}{200}\) x \(\frac{5}{11}\)
\(\frac74\) x \(\frac{3}{x}\) = \(\frac{21}{40}\)
\(\frac{3}{x}\) = \(\frac{21}{40}\) : \(\frac74\)
\(\frac{3}{x}\) = \(\frac{21}{40}\) x \(\frac47\)
\(\frac{3}{x}\) = \(\frac{3}{10}\)
\(x=3:\frac{3}{10}\)
\(x=3\times\frac{3}{10}\)
\(x=10\)
\(\frac{1}{2}:\frac{3}{2}:\frac{5}{4}:\frac{6}{5}:\frac{7}{6}:\frac{8}{7}\)
\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{7}\cdot\frac{7}{8}\)
\(=\frac{1\cdot\left(2\cdot5\cdot6\cdot7\right)}{8\cdot3\cdot\left(2\cdot5\cdot6\cdot7\right)}\)
\(=\frac{1}{24}\)
\(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{7}\cdot\frac{7}{8}\cdot\frac{8}{9}\cdot\frac{9}{10}\)
\(=\frac{1\cdot\left(2\cdot3\cdot4\cdot5\cdot6\cdot7\cdot8\cdot9\right)}{\left(2\cdot3\cdot4\cdot5\cdot6\cdot7\cdot8\cdot9\right)\cdot10}\)
\(=\frac{1}{10}\)