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a)\(\dfrac{x}{7}=\dfrac{18}{14}\)
\(\Rightarrow x=\dfrac{7.18}{14}=9\)
b)\(6:x=1\dfrac{3}{4}\)
\(\Leftrightarrow\dfrac{6}{x}=\dfrac{7}{4}\)
\(\Rightarrow x=\dfrac{6.4}{7}=\dfrac{24}{7}\)
c)5,7:0,35=(-x):0,45
\(\Leftrightarrow\dfrac{114}{7}=\dfrac{-x}{0,45}\)
\(\Rightarrow\left(-x\right)=\dfrac{114.0,45}{7}=\dfrac{-513}{70}\)
a/ \(\dfrac{x}{7}=\dfrac{18}{14}\)
\(\Leftrightarrow14x=7.18\)
\(\Leftrightarrow14x=126\)
\(\Leftrightarrow x=9\)
Vậy ....
b/ \(6:x=1\dfrac{3}{4}:5\)
\(\Leftrightarrow6:x=\dfrac{7}{20}\)
\(\Leftrightarrow x=\dfrac{120}{7}\)
Vậy ...........
a) \(\frac{x}{7}=\frac{18}{14}\)
\(\frac{x}{7}=\frac{9}{7}\)
\(\Rightarrow x=9\)
b) \(6:x=1\frac{3}{4}:5\)
\(6:x=\frac{7}{4}.\frac{1}{5}\)
\(6:x=\frac{7}{20}\)
\(x=6:\frac{7}{20}\)
\(x=\frac{120}{7}\)
vay \(x=\frac{120}{7}\)
c) \(\frac{5,7}{0,35}=\frac{-x}{0,45}\)
\(\Rightarrow-0,35x=5,7.0,45\)
\(\Rightarrow-0,35x=2,565\)
\(\Rightarrow x=\frac{-2,565}{0,35}\)
\(\Rightarrow x=\frac{-513}{70}\)
vay \(x=\frac{-513}{70}\)
a)\(\dfrac{x}{3}=\dfrac{y}{7}=\dfrac{x+y}{3+7}=\dfrac{20}{10}=2\)
\(\dfrac{x}{3}=2\Rightarrow x=6\)
\(\dfrac{y}{7}=2\Rightarrow y=14\)
b)\(\dfrac{x}{5}=\dfrac{y}{2}=\dfrac{x-y}{5-2}=\dfrac{6}{3}=2\)
\(\dfrac{x}{5}=2\Rightarrow x=10\)
\(\dfrac{y}{2}=2\Rightarrow y=4\)
Câu 2:
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{2}=\dfrac{y}{4}=\dfrac{z}{6}=\dfrac{x-y+z}{2-4+6}=\dfrac{8}{8}=1\)
Do đó: x=2; y=4; z=6
a)x=18*7/14=9
b)x=6.5/(7/4)=120/7
c)-x=5,7*0,45/0,35=513/70
\(\begin{array}{l}a)\dfrac{x}{6} = \dfrac{{ - 3}}{4}\\x = \dfrac{{( - 3).6}}{4}\\x = \dfrac{{ - 9}}{2}\end{array}\)
Vậy \(x = \dfrac{{ - 9}}{2}\)
\(\begin{array}{l}b)\dfrac{5}{x} = \dfrac{{15}}{{ - 20}}\\x = \dfrac{{5.( - 20)}}{{15}}\\x = \dfrac{{ - 20}}{3}\end{array}\)
Vậy \(x = \dfrac{{ - 20}}{3}\)
1 a) \(\dfrac{\left(-2\right)}{5}\)= \(\dfrac{-6}{15}\); \(\dfrac{15}{-6}\)= \(\dfrac{5}{-2}\); \(\dfrac{-6}{-2}\)= \(\dfrac{15}{5}\); \(\dfrac{-2}{-6}\)= \(\dfrac{5}{15}\)
a) \(\frac{x}{7}=\frac{18}{14}\)
\(\Rightarrow\frac{x}{7}=\frac{9}{7}\)
\(\Rightarrow x=7\)
Vậy x=7
b)\(6:x=1\frac{3}{4}:5\)
\(\frac{6}{x}=\frac{7}{4}:5\)
\(\frac{6}{x}=\frac{7}{20}\)
\(\Rightarrow6.20=7x\)
\(\Rightarrow120=7.x\)
\(\Rightarrow x=\frac{120}{7}\)
Vậy \(x=\frac{120}{7}\)
\(a,x=\dfrac{18.7}{14}\)
\(x=\dfrac{8}{2}=4\)
\(b,\)\(x=6.5:1\dfrac{3}{4}\)
\(x=30:\dfrac{7}{4}\)
\(x=30.\dfrac{4}{7}=\dfrac{120}{7}\)
\(c,-x=\)\(\dfrac{5,7.0,45}{0,35}\)
\(-x=\)\(\dfrac{2,565}{0,35}\)
\(x=\dfrac{-2,565}{0,35}\)
a)\(\dfrac{x}{7}=\dfrac{18}{14}\) b) 6:x=\(1\dfrac{3}{4}\):5 c) 5,7 : 0,35= -x: 0,45
\(\Rightarrow\) x.14= 18.7 \(\Rightarrow\) 6:x=\(\dfrac{7}{20}\) \(\Rightarrow\)\(\dfrac{114}{7}=\dfrac{-x}{0,45}\)
\(\Rightarrow\)x.14=126 \(\Rightarrow\)x=\(\dfrac{10}{21}\) \(\Rightarrow53,1=\left(-x\right).7\)
\(\Rightarrow\)x=9 \(\Rightarrow x=7,3\)
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