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\(2\frac{3}{13}\cdot\frac{26}{58}\cdot4\cdot2\frac{15}{24}\cdot\frac{8}{21}=\frac{29}{13}\cdot\frac{26}{58}\cdot4\cdot\frac{21}{8}\cdot\frac{8}{21}=\frac{29\cdot26\cdot4\cdot21\cdot8}{13\cdot58\cdot8\cdot21}=\frac{1\cdot2\cdot4\cdot1\cdot1}{1\cdot2\cdot1\cdot1}=\frac{1\cdot4}{1}=4\)
{9/5-3/5} : {15/3-11/5}
6/5:14/5
6/5x5/14=3/7
Câu 2:
{2/1x3+2/3x5+...+2/19x21} x{1/28-5/2x1/70}
{2/1x3+2/3x5+...+2/19x21} x{1/28-1/28}
{2/1x3+2/3x5+...+2/19x21} x0=0
\(\frac{x}{27}-\frac{2}{9}=\frac{6}{18}\Rightarrow\frac{x}{27}=\frac{5}{9}\Rightarrow x=15\)
máy tính đang để ở nhà ông anh , làm biếng tính tay lắm, đành tính nhẩm vậy, còn mấy bài kia tự xử nhé
Tim x:
x X 12 + x X 14 + x X 18 = \(\frac{21}{24}\)
x X (\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}\)) = \(\frac{21}{24}\)
x X (\(\frac{4}{8}+\frac{2}{8}+\frac{1}{8}\)) = \(\frac{21}{24}\)
x X \(\frac{9}{8}\)= \(\frac{21}{24}\)
x = \(\frac{21}{24}\): \(\frac{9}{8}\)
x = \(\frac{21}{24}\)X \(\frac{8}{9}\)
x = \(\frac{7}{9}\)
\(x\times\frac{1}{2}+x\times\frac{1}{4}+x\times\frac{1}{8}=\frac{21}{24}\)
\(\Rightarrow x\times\left[\frac{1}{2}+\frac{1}{4}+\frac{1}{8}\right]=\frac{21}{24}\)
\(\Rightarrow x\times\left[\frac{4+2+1}{8}\right]=\frac{21}{24}\)
\(\Rightarrow x\times\frac{7}{8}=\frac{21}{24}\)
\(\Rightarrow x\times\frac{7}{8}=\frac{7}{8}\)
\(\Rightarrow x=\frac{7}{8}:\frac{7}{8}=1\)
a) X = 15
b) X = 4
c ) X= 23
d) X= 11
( Chỉ là ý kiến riêng thôi nhé, nhận gạch đá )
a) \(\frac{6+x}{33}=\frac{7}{11}\)
=> (6 + x). 11 = 33.7
=> 66 + 11x = 231
=> 11x = 231 - 66
=> 11x = 165
=> x = 165 : 11
=> x = 15
b) 15/26 + x/13 = 46/52
=> x/13 = 23/26 - 15/26
=> x/13 = 4/13
=> x = 4
c) 121/27 x 54/11 < x < 100/21 : 25/126
=> 22 < x < 24
=> x = 23 (vì x là số tự nhiên)
d) 1 < 11/x < 12
=> 11/x \(\in\){2; 3; 4 ; ...; 11}
=> x \(\in\) {11/2; 11/3; ...; 1}
Vì x là số tự nhiên => x = 1
a) \(\frac{24}{x}=\frac{3}{5}.\frac{8}{3}\)
\(\frac{24}{x}=\frac{8}{5}\)
\(x=\frac{24.5}{8}\)
\(x=15\)
b) \(2.x=24\frac{1}{4}-3\frac{1}{2}\)
\(2.x=\frac{83}{4}\)
\(x=\frac{83}{8}\)
Câu c, d làm tương tự, đơn giản
\(\dfrac{3}{4}\times\dfrac{8}{5}:1\dfrac{1}{6}\)
=\(\dfrac{6}{5}:\) \(\dfrac{7}{6}\)
=\(\dfrac{6}{5}\times\dfrac{6}{7}=\dfrac{36}{35}\)
2\(\dfrac{1}{3}\) x 1\(\dfrac{1}{4}\) -\(\dfrac{7}{5}\)
\(\dfrac{7}{3}\times\dfrac{5}{4}-\) \(\dfrac{7}{5}\)
\(\dfrac{35}{12}-\dfrac{7}{5}\)
\(\dfrac{175}{60}-\dfrac{84}{60}=\dfrac{91}{60}\)
4\(\dfrac{2}{3}+1\dfrac{1}{4} +2\dfrac{1}{3}+2\dfrac{3}{7}\)
(4 +2) + \(\left(\dfrac{2}{3}+\dfrac{1}{3}\right)\) +1\(\dfrac{1}{4}\) + \(2\dfrac{3}{7}\)
6 + 1 + \(\dfrac{5}{4}\) + \(\dfrac{17}{7}\)
7 + \(\dfrac{103}{28}\)
\(\dfrac{299}{28}\)
\(2\times\frac{3}{13}\times\frac{26}{58}\times4\times2\frac{15}{24}\times\frac{8}{21}\)
\(=\left(2\times4\right)\times\left(\frac{3}{13}\times\frac{26}{58}\times\frac{63}{24}\times\frac{8}{21}\right)\)
\(=8\times\left(\frac{3\times26\times63\times8}{13\times58\times24\times21}\right)\)
\(=8\times\left(\frac{3\times13\times2\times7\times3\times3\times8}{13\times29\times2\times3\times8\times7\times3}\right)\)
\(=8\times\left(\frac{2\times3\times8}{29}\right)\)
\(=8\times\left(\frac{48}{29}\right)\)
\(=\frac{8\times48}{29}\)
\(=\frac{384}{29}=13\frac{7}{29}\)