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21 tháng 6 2017

a) \(\dfrac{x+1}{32}=\dfrac{2}{x+1}\)

\(\Leftrightarrow\dfrac{x+1}{32}=\dfrac{2}{x+1}\left(đk:x\ne1\right)\)

\(\Leftrightarrow\left(x+1\right)\left(x+1\right)=64\)

\(\Leftrightarrow\left(x+1\right)^2-64=0\)

\(\Leftrightarrow x^2+2x+1-64=0\)

\(\Leftrightarrow x^2+6x-63=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-2+16}{2}\\x=\dfrac{-2-16}{2}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=7\\x=-9\end{matrix}\right.\left(đk:x\ne-1\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}x=7\\x=-9\end{matrix}\right.\)

Vậy \(x_1=-9;x_2=7\)

b) \(\dfrac{x+1}{5}=\dfrac{7}{x-1}\)

\(\Leftrightarrow\dfrac{x+1}{5}=\dfrac{7}{x-1}\left(đk:x\ne1\right)\)

\(\Leftrightarrow\left(x+1\right)\left(x-1\right)=35\)

\(\Leftrightarrow\left(x+1\right)\left(x-1\right)-35=0\)

\(\Leftrightarrow x^2-1-35=0\)

\(\Leftrightarrow x^2-36=0\)

\(\Leftrightarrow x^2=36\)

\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\left(đk:x\ne1\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)

Vậy \(x_1=-6;x_2=6\)

c) \(\left|4,5-2x\right|:1\dfrac{7}{4}=\dfrac{11}{14}\)

\(\Leftrightarrow\left|4,5-2x\right|:\dfrac{11}{4}=\dfrac{11}{4}\)

\(\Leftrightarrow\left|4,5-2x\right|\cdot\dfrac{4}{11}=\dfrac{11}{14}\)

\(\Leftrightarrow\dfrac{4}{11}\cdot\left|4,5-2x\right|=\dfrac{11}{14}\)

\(\Leftrightarrow\left|4,5-2x\right|=\dfrac{121}{56}\)

\(\Leftrightarrow\left[{}\begin{matrix}4,5-2x=\dfrac{121}{56}\\4,5-2x=-\dfrac{121}{56}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{131}{112}\\x=\dfrac{373}{112}\end{matrix}\right.\)

Vậy \(x_1=\dfrac{131}{112};x_2=\dfrac{373}{112}\)

21 tháng 6 2017

a) \(\dfrac{x+1}{32}=\dfrac{2}{x+1}\)

\(\Rightarrow\left(x+1\right)\left(x+1\right)=32.2\)

\(\Rightarrow\left(x+1\right)^2=64\)

\(\Rightarrow\left(x+1\right)^2=8^2\)

\(\Rightarrow x+1=8\)

\(\Rightarrow x=8-1\)

\(\Rightarrow x=7\left(TM\right)\)

Vậy \(x=7\) là giá trị cần tìm

b) \(\dfrac{x+1}{5}=\dfrac{7}{x-1}\)

\(\Rightarrow\left(x+1\right)\left(x-1\right)=7.5\)

\(\Rightarrow\left[{}\begin{matrix}x+1=7\\x-1=5\end{matrix}\right.\) \(\Rightarrow x=6\left(TM\right)\)

Vậy \(x=6\) là giá trị cần tìm

c) \(\left|4,5-2x\right|:1\dfrac{7}{4}=\dfrac{11}{14}\)

\(\left|\dfrac{45}{10}-2x\right|:\dfrac{11}{4}=\dfrac{11}{4}\)

\(\left|\dfrac{9}{2}-2x\right|=\dfrac{11}{14}.\dfrac{11}{4}\)

\(\left|\dfrac{9}{2}-2x\right|=\dfrac{121}{56}\)

\(\Rightarrow\left[{}\begin{matrix}\dfrac{9}{2}-2x=\dfrac{121}{56}\\\dfrac{9}{2}-2x=\dfrac{-121}{56}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}2x=\dfrac{131}{56}\\2x=\dfrac{373}{56}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{131}{112}\\x=\dfrac{373}{112}\end{matrix}\right.\)

Vậy \(x\in\left\{\dfrac{131}{112};\dfrac{373}{112}\right\}\) là giá trị cần tìm

d: =>-x-5/6=7/12-4/12=3/12=1/4

=>-x=1/4+5/6=13/12

hay x=-13/12

e: =>x+3=-5

hay x=-8

f: =>4,5-2x=-1/2

=>2x=5

hay x=5/2

8 tháng 3 2022

nhanh v ???

16 tháng 7 2021

`a)(4,5-2x)*1 4/7=11/14`

`=>(4,5-2x)*11/7=11/14`

`=>4,5-2x=1/2`

`=>2x=4,5-0,5=4`

`=>x=2`

Vậy `x=2`

`b)(2,8x-32):2/3=-90`

`=>2,8x-32=-90*2/3=-60`

`=>2,8x=-28`

`=>x=-10`

Vậy `x=-10`

a:=>0,75x-x+1,25x=0,2

=>x=0,2

b: =>1/3-x=-3/6+4/6=1/6

=>x=1/3-1/6=1/6

c: =>(x-1)/45=-6/30=-1/5

=>x-1=-9

=>x=-8

d: =>(2/5x-1)=-5/7

=>2/5x=2/7

=>x=5/7

25 tháng 4 2022

tham khảo

cái này đúng không nhỉ 

25 tháng 4 2022

4,5 -2x = 11/14 : 1 4/7

4,5 -2x = 11/14 : 11/7

4,5 -2x =  1/2

2x = 4,5 - 1/2

2x = 4

x = 4 : 2

x = 2

a: =>x-3/4=1/6-1/2=1/6-3/6=-2/6=-1/3

=>x=-1/3+3/4=-4/12+9/12=5/12

b: =>x(1/2-5/6)=7/2

=>-1/3x=7/2

hay x=-21/2

c: (4-x)(3x+5)=0

=>4-x=0 hoặc 3x+5=0

=>x=4 hoặc x=-5/3

d: x/16=50/32

=>x/16=25/16

hay x=25

e: =>2x-3=-1/4-3/2=-1/4-6/4=-7/4

=>2x=-7/4+3=5/4

hay x=5/8

a: \(A=\dfrac{-7}{28}\cdot\dfrac{15}{25}=\dfrac{-1}{4}\cdot\dfrac{3}{5}=\dfrac{-3}{20}\)

b: \(B=\dfrac{-5\cdot7}{14\cdot\left(-3\right)}=\dfrac{35}{42}=\dfrac{5}{6}\)

c: \(C=\dfrac{-1}{5}-\dfrac{1}{5}\cdot\dfrac{3}{5}=\dfrac{-1}{5}-\dfrac{3}{25}=\dfrac{-8}{25}\)

d: \(D=\dfrac{-3}{4}-\dfrac{1}{4}=-1\)

e: \(E=\dfrac{-4}{5}\left(1-\dfrac{15}{16}\right)=\dfrac{-4}{5}\cdot\dfrac{1}{16}=\dfrac{-1}{20}\)

f: \(F=\dfrac{6-7}{4}\cdot\dfrac{4+12}{22}=\dfrac{-1}{4}\cdot\dfrac{8}{11}=\dfrac{-2}{11}\)

12 tháng 5 2021

a/  => \(\dfrac{3}{5}.\dfrac{1}{x}=\dfrac{6}{25}\)

=> \(\dfrac{1}{x}=\dfrac{2}{5}\)

=> x = 5/2

b/ \(\Rightarrow2\left(x-\dfrac{1}{3}\right)=\dfrac{2}{15}\)

=> \(x-\dfrac{1}{3}=\dfrac{1}{15}\)

=> \(x=\dfrac{2}{5}\)

c/ => | x + 1| = 10/21

=> \(\left[{}\begin{matrix}x=-\dfrac{11}{21}\\x=-\dfrac{31}{21}\end{matrix}\right.\)

 

d/ => \(5x+5=6x-3\)

=> x = 8

19 tháng 5 2022

tách đi bạn

19 tháng 5 2022

a) (2x - 3)(6 - 2x) = 0

=> \(\left[{}\begin{matrix}2x-3=0\\6-2x=0\end{matrix}\right.=>\left[{}\begin{matrix}2x=3\\2x=6\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=3\end{matrix}\right.\)

b) \(5\dfrac{4}{7}:x=13=>\dfrac{39}{7}:x=13=>x=\dfrac{39}{7}:13=>x=\dfrac{3}{7}\)

c) \(2x-\dfrac{3}{7}=6\dfrac{2}{7}=>2x-\dfrac{3}{7}=\dfrac{44}{7}=>2x=\dfrac{47}{7}=>x=\dfrac{47}{14}\)

d) \(\dfrac{x}{5}+\dfrac{1}{2}=\dfrac{6}{10}=>\dfrac{x}{5}=\dfrac{6}{10}-\dfrac{1}{2}=>\dfrac{x}{5}=\dfrac{1}{10}=>x.10=5=>x=\dfrac{1}{2}\)

e) \(\dfrac{x+3}{15}=\dfrac{1}{3}=>\left(x+3\right).3=15=>x+3=5=>x=2\)