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\(a,\dfrac{3}{8}=\dfrac{6}{x}\\ \Rightarrow x=6:\dfrac{3}{8}\\ \Rightarrow x=16\\ b,\dfrac{1}{9}=\dfrac{x}{27}\\ \Rightarrow x=\dfrac{1}{9}.27\\ \Rightarrow x=3\\ c,\dfrac{4}{x}=\dfrac{8}{6}\\ \Rightarrow x=4:\dfrac{4}{3}\\ \Rightarrow x=3\\ d,\dfrac{3}{x-5}=\dfrac{-4}{x+2}\\ \Rightarrow3\left(x+2\right)=-4\left(x-5\right)\\ \Rightarrow3x+6=-4x+20\\ \Rightarrow3x+6+4x-20=0\\ \Rightarrow7x-14=0\\ \Rightarrow7x=14\\ \Rightarrow x=2\)
a: =>6/x=3/8
hay x=16
b: =>x/27=1/9
nên x=3
c: =>4/x=4/3
nên x=3
d: =>3/x-5=-4/x+2
=>3x+2=-4x+20
=>7x=18
hay x=18/7
\(\left(x-1\right)^4:3^2=3^6\)
\(\left(x-1\right)^4=3^6.3^2\)
\(\left(x-1\right)^4=3^8\)
\(\left(x-1\right)^4=3^{2.4}=\left(3^2\right)^4=9^4\)
\(\Rightarrow\orbr{\begin{cases}x-1=9\\x-1=-9\end{cases}\Rightarrow\orbr{\begin{cases}x=9+1=10\\x=-9+1=-8\end{cases}}}\)
Vậy: \(\orbr{\begin{cases}x=10\\x=-8\end{cases}}\)
( x - 1 )4 : 32 = 36
( x - 1 )4 = 36 . 32
( x - 1 )4 = 38
( x - 1 )4 = 6561
( x - 1 )4 = 94
x - 1 = 9
x = 10
\(\dfrac{3}{x-5}=\dfrac{-4}{x+2}\)=>3.(x+2)=(x-5).(-4)
=> 3.2+3.x=x.(-4)-(-4).5
=>6+3.x=x.(-4)-(-20)
=>3.x-x.(-4)=20-6
=>3.x-x.(-4)=14
=>x.(3+4)=14(vì 3-(-4)=3+4)
=>x.7=14
=>x=14:7
=>x=2
12x/6 + 4x/6 - 3x/6 = 3/8 - 1/4 - 1/6
13x/6 = (9 - 6 - 4)/24 = -1/24
--> x = -1/52
- a, Do \(\left[3x-15\right]^7=0\)
=> \(3x-15=0\)
=> \(3x=0+15\)
=> \(3x=15\)
=> \(x=15:3\)
=> \(x=5\)
\(\left(3x-5\right)^7=0\)
\(\Rightarrow3x-5=0\)
\(\Rightarrow3x=5\)
\(\Rightarrow x=\frac{5}{3}\)
\(a,0.25x\) - \(\frac{2}{3}x\) =\(1\frac{1}{6}\)
\(\Rightarrow x\cdot\left(0.25-\frac{2}{3}\right)=1\frac{1}{6}\)
\(\Rightarrow x\cdot\frac{-5}{12}=\frac{7}{6}\)
\(\Rightarrow x=\frac{7}{6}:\frac{-5}{12}\)
\(\Rightarrow x=\frac{-14}{5}=-2.8\)