a: =>3/2x=64/15

=>x=128/45

b: =>-1/6x=7/12

=>x=-7/2

c: =>11/2*x=1/2

=>x=1/2:11/2=1/11

a, \(\dfrac{x}{12}-\dfrac{5}{6}=\dfrac{1}{12}\)

\(\Rightarrow\dfrac{x}{12}=\dfrac{1}{12}+\dfrac{5}{6}\)

\(\Rightarrow\dfrac{x}{12}=\dfrac{11}{12}\)

\(\Rightarrow x=11\)

b, \(\dfrac{2}{3}-1\dfrac{4}{15}x=\dfrac{-3}{5}\)

\(\Rightarrow\dfrac{2}{3}-\dfrac{19}{15}x=\dfrac{-3}{5}\)

\(\Rightarrow\dfrac{19}{15}x=\dfrac{2}{3}+\dfrac{3}{5}\)

\(\Rightarrow\dfrac{19}{15}x=\dfrac{19}{15}\)

\(\Rightarrow x=1\)

c, \(-2^3+0,5x=1,5\)

\(\Rightarrow-8+\dfrac{1}{2}x=\dfrac{3}{2}\)

\(\Rightarrow\dfrac{1}{2}x=\dfrac{3}{2}+8\)

\(\Rightarrow\dfrac{1}{2}x=\dfrac{19}{2}\)

\(\Rightarrow x=19\)

1) \(\dfrac{x}{12}-\dfrac{5}{6}=\dfrac{1}{12}\) 2)\(\dfrac{2}{3}-1\dfrac{4}{15}x=\dfrac{-3}{5}\) \(\dfrac{x}{12}=\dfrac{1}{12}+\dfrac{5}{6}\) \(\dfrac{2}{3}-\dfrac{19}{15}x=\dfrac{-3}{5}\) \(\dfrac{x}{12}=\dfrac{11}{12}\) \(\dfrac{19}{15}x=\dfrac{2}{3}-\left(\dfrac{-3}{5}\right)\) => \(x=11\) \(\dfrac{19}{15}x=\dfrac{19}{15}\) => \(x=1\) 3) -2³ + 0,5x = 1,5 -8 + 0,5x = 1,5 0,5x = 1,5 - (-8) 0,5x = 9,5 x = 9,5 : 0,5 x = 19

Tìm x:

a, x+30%=-1,3

<=> x+0,3=-1,3

<=> x=-1,3-0,3

<=> x=-1,6

Vậy x=-1,6

b, 0,5x-\(\dfrac{2}{3}x\) =\(\dfrac{7}{12}\)

<=>\(\dfrac{-1}{6}x\)=\(\dfrac{7}{12}\)

<=> x=\(\dfrac{-7}{2}\)

Vậy x=\(\dfrac{-7}{2}\)

Lời giải:

PT $\Leftrightarrow 0,4+0,2x-0,5x=0,25-0,5x+0,25$

$\Leftrightarrow 0,4-0,3x=0,5-0,5x$

$\Leftrightarrow 0,2x=0,1\Rightarrow x=0,5$

a) \(\dfrac{x}{3}-\dfrac{2x+1}{2}=\dfrac{x}{6}-x\)

\(\Leftrightarrow\dfrac{2x}{6}-\dfrac{3\left(2x+1\right)}{6}=\dfrac{x}{6}=\dfrac{6x}{6}\)

\(\Leftrightarrow2x-3\left(2x+1\right)=x-6x\)

\(\Leftrightarrow2x-6x-3=x-6x\)

\(\Leftrightarrow2x-6x-x+6x=3\)

\(\Leftrightarrow x=3\)

\(S=\left\{3\right\}\)

b) \(\dfrac{2+x}{5}-0,5x=\dfrac{1-2x}{4}+0,25\)

\(\Leftrightarrow\dfrac{4\left(2+x\right)}{20}-\dfrac{10x}{20}=\dfrac{5\left(1-2x\right)}{20}+\dfrac{5}{20}\)

\(\Leftrightarrow4\left(2+x\right)-10x=5\left(1-2x\right)+5\)

\(\Leftrightarrow8+4x-10x=5-10x+5\)

\(\Leftrightarrow4x-10x+10x=5+5-8\)

\(\Leftrightarrow4x=2\)

\(\Leftrightarrow x=\dfrac{1}{2}\)

\(S=\left\{\dfrac{1}{2}\right\}\)

a)X= 3

b)X= 0,5

\(\dfrac{2+x}{5}-0,5x=\dfrac{1-2x}{4}+0,25\)

\(\Leftrightarrow\dfrac{2+x}{5}-\dfrac{x}{2}=\dfrac{1-2x}{4}+\dfrac{1}{4}\)

\(\Leftrightarrow\dfrac{2+x}{5}-\dfrac{x}{2}=\dfrac{1-2x+1}{4}\)

\(\Leftrightarrow\dfrac{2+x}{5}-\dfrac{x}{2}=\dfrac{2-2x}{4}\)

\(\Leftrightarrow\dfrac{2+x}{5}=\dfrac{1-x}{2}+\dfrac{x}{2}\)

\(\Leftrightarrow\dfrac{2+x}{5}=\dfrac{1-x+x}{2}\)

\(\Leftrightarrow\dfrac{2+x}{5}=\dfrac{1}{2}\)

\(\Leftrightarrow2\left(2+x\right)=5\\ \Leftrightarrow2x+4-5=0\\ \Leftrightarrow2x-1=0\\ \Leftrightarrow x=\dfrac{1}{2}\)

\(PT.\Rightarrow\) \(\dfrac{8+4x-10x-5+10x-5}{20}=0.\Rightarrow4x=2.\Leftrightarrow x=\dfrac{1}{2}.\)

\(\dfrac{2+x}{5}-0,5x=\dfrac{1-2x}{4}+0,25\\ \Leftrightarrow\dfrac{4.\left(2+x\right)}{20}-\dfrac{20.0,5x}{20}=\dfrac{5.\left(1-2x\right)}{20}+\dfrac{0,25.20}{20}\\ \Leftrightarrow8+4x-10x=5-10x+5\\ \Leftrightarrow4x=2\\ \Leftrightarrow x=\dfrac{1}{2}\\ \Rightarrow S=\left\{\dfrac{1}{2}\right\}\)

1: \(\Leftrightarrow\left(x+1\right)^2=4\)

=>x+1=2 hoặc x+1=-2

=>x=1 hoặc x=-3

2: \(\Leftrightarrow7x-21=5x+25\)

=>2x=46

=>x=23

3: \(\Leftrightarrow x^2+4x+3=x^2+0.5x+4x+2\)

=>4,5x+2=4x+3

=>x=1

=>1/2:(0,5x-1,5)=0,2-0,35=-0,15=-3/20

=>0,5x-1,5=1/2:(-3/20)=-1/2*20/3=-10/3

=>0,5x=-10/3+3/2=-11/6

=>x=-11/3