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a: \(=\dfrac{-3}{7}+\dfrac{-9}{35}-\dfrac{2}{5}\)
\(=\dfrac{-15-9-14}{35}=\dfrac{-38}{35}\)
b: \(=\left(\dfrac{15}{24}-\dfrac{7}{12}\right)\cdot\dfrac{-12}{7}\)
\(=\dfrac{15-14}{24}\cdot\dfrac{-12}{7}=\dfrac{1}{24}\cdot\dfrac{-12}{7}=\dfrac{-1}{14}\)
c: \(=\dfrac{7}{5}\cdot\dfrac{15}{19}\cdot\dfrac{-8}{15}+\dfrac{7}{15}\)
\(=\dfrac{-56}{95}+\dfrac{7}{15}\)
\(=\dfrac{-7}{57}\)
\(\frac{x+3}{15}=\frac{1}{3}\)
\(\Rightarrow x+3=\frac{1}{3}\cdot15\)
\(\Rightarrow x=5-3\)
\(\Rightarrow x=2\)
\(\frac{x+3}{15}=\frac{1}{3}\)
\(x+3=\frac{1}{3}\times15\)
x+3=5
x=5-3
x=2
\(\dfrac{-5}{6}\)- x=\(\dfrac{7}{12}\)+\(\dfrac{-8}{12}\)=\(\dfrac{-15}{12}\)
\(\Rightarrow\)x=\(\dfrac{-5}{6}\)-\(\dfrac{-15}{12}\)=\(\dfrac{-10}{12}\)-\(\dfrac{-15}{12}\)=\(\dfrac{-25}{12}\)
a: =>15-(x-2)=-13-27=-40
=>x-2=15+40=55
hay x=57
b: =>5-x=-114+12=-102
=>x=107
c: \(\Leftrightarrow\left|x\right|=-1-5=-6\)(vô lý)
d: \(\Leftrightarrow\left|x-3\right|=3\)
=>x-3=3 hoặc x-3=-3
=>x=6 hoặc x=0
b, \(\dfrac{x-3}{4}=\dfrac{15}{20}\)
<=> \(\dfrac{x-3}{4}=\dfrac{3}{4}\)
=> x-3=3
<=> x=6
Vậy x=6
\(a,\dfrac{x}{15}=\dfrac{4}{y}=\dfrac{-2}{5}\)
* \(\dfrac{x}{15}=\dfrac{-2}{5}\)
\(\Rightarrow\dfrac{x}{15}=\dfrac{-6}{15}\)
\(\Rightarrow x=-6\)
*\(\dfrac{4}{y}=\dfrac{-2}{5}\)
\(\Rightarrow\dfrac{4}{y}=\dfrac{4}{-10}\)
\(\Rightarrow y=-10\)
Vậy x = - 6 ; y = - 10
\(b,\dfrac{x-3}{4}=\dfrac{15}{20}\)
=> ( x - 3 ) . 20 = 4. 15
=> 20x - 60 = 60
=> 20x = 60 + 60
=> 20x = 120
=> x = 120 : 20
=> x = 6
Vậy x = 6
\(c,\dfrac{-5}{9}+\dfrac{-8}{15}+\dfrac{22}{-9}+\dfrac{-7}{15}< x\le\dfrac{-1}{3}+\dfrac{-1}{4}+\dfrac{-5}{12}\)
\(\Rightarrow\dfrac{-5}{9}+\dfrac{-8}{15}+\dfrac{-22}{9}+\dfrac{-7}{15}< x\le\dfrac{-4}{12}+\dfrac{-3}{12}+\dfrac{-5}{12}\)
\(\Rightarrow\left(\dfrac{-5}{9}+\dfrac{-22}{9}\right)+\left(\dfrac{-8}{15}+\dfrac{-7}{15}\right)< x\le-1\)
\(\Rightarrow-3+\left(-1\right)< x\le-1\)
\(\Rightarrow-4< x\le-1\)
\(\Rightarrow x=-3;-2;-1\)
\(\frac{2}{3}.x-\frac{1}{4}.x=\frac{15}{12}\)
\(x.\left(\frac{2}{3}-\frac{1}{4}\right)=\frac{15}{12}\)
\(x.\frac{5}{12}=\frac{15}{12}\)
\(x=\frac{15}{12}:\frac{5}{12}\)
\(x=3\)
\(\frac{2}{3}x-\frac{1}{2}x=\frac{15}{12}\)
\(x\left(\frac{2}{3}-\frac{1}{2}\right)=\frac{5}{4}\)
\(x\frac{1}{6}=\frac{5}{4}\)
\(x=\frac{5}{4}:\frac{1}{6}\)
\(x=\frac{15}{2}\)
\(x\div3\frac{1}{15}=1\frac{1}{12}\)
\(\Leftrightarrow x\div\frac{46}{15}=\frac{13}{12}\)
\(\Leftrightarrow x=\frac{13}{12}\times\frac{46}{15}\)
\(\Leftrightarrow x=\frac{598}{180}\)
\(\Leftrightarrow x=\frac{299}{90}\)
3x - 12 = 15
3x = 27
3x = 33
x = 3
`3^x -12=15`
`3^x=15+12`
`3^x=27`
`3^x = 3^3`
`=> x = 3`