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30 tháng 7 2016

\(\frac{-2}{x}=\frac{-x}{\frac{8}{25}}\)

=>\(\left(-x\right)x=\left(-2\right).\frac{8}{25}\)

=>\(-x^2=-\frac{16}{25}\)

=>\(x^2=\frac{16}{25}\)

=>\(x=-\frac{4}{5}\) hoặc \(x=\frac{4}{5}\)

30 tháng 7 2016

\(-\frac{2}{x}=-\frac{x}{\frac{8}{25}}\Rightarrow-2.-\frac{8}{25}=x^2\Rightarrow\frac{16}{25}=x^2\Rightarrow x=\frac{\sqrt{16}}{\sqrt{25}}=\frac{4}{5}\)

31 tháng 7 2016

a) Lm r nkoa!

b) \(\left(0,25x\right):3=\frac{5}{6}:0,125\)

\(=\left(0,25x\right):3=\frac{20}{3}\)

\(\Rightarrow0,25x=\frac{20}{3}\cdot3=20\)

\(\Rightarrow x=20:0,25=80\)

\(\Rightarrow x=80\)

c) \(0,01:2,5=\left(0,75x\right):0,75\)

\(=\frac{1}{250}=\left(0,75x\right):0,75\)

\(\Rightarrow0,75x=\frac{1}{250}\cdot0,75=\frac{3}{1000}\)

\(\Rightarrow x=\frac{3}{1000}:0,75=\frac{1}{250}\)

\(\Rightarrow x=\frac{1}{250}\)

d) \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1x\right)\)

\(=\frac{5}{3}=\frac{2}{3}:\left(0,1x\right)\)

\(\Rightarrow0,1x=\frac{2}{3}:\frac{5}{3}=\frac{2}{5}\)

\(\Rightarrow x=\frac{2}{5}:0,1=4\)

\(\Rightarrow4\)

18 tháng 7 2016

a) \(\frac{2}{3}-\frac{1}{3}\left(x-\frac{3}{2}\right)-\frac{1}{2}\left(2x+1\right)=5\)\(5\)

=> \(\frac{2}{3}-\left(\frac{1}{3}x-\frac{1}{2}\right)-\left(x+\frac{1}{2}\right)=5\)

=>\(\frac{2}{3}-\frac{1}{3}x+\frac{1}{2}-x-\frac{1}{2}=5\)

=>\(\left(\frac{2}{3}+\frac{1}{2}-\frac{1}{2}\right)-\left(\frac{1}{3}x+x\right)=5\)

=>\(\frac{2}{3}-\frac{4}{3}x=5\)

=>\(\frac{4}{3}x=\frac{2}{3}-5=-\frac{13}{3}\)

=>\(x=-\frac{13}{3}:\frac{4}{3}=-\frac{13}{4}\)

b)\(4x-\left(x+\frac{1}{2}\right)=2x-\left(\frac{1}{2}-5\right)\)

=>\(4x-x-\frac{1}{2}=2x-\left(-\frac{9}{2}\right)\)

=> \(3x-\frac{1}{2}=2x-\left(-\frac{9}{2}\right)\)

=>\(x=-\left(-\frac{9}{2}\right)+\frac{1}{2}=5\)

16 tháng 7 2017

a) \(\left(x+\frac{1}{3}\right)^3=\frac{-8}{27}\)

\(\left(x+\frac{1}{3}\right)^3=\left(\frac{-2}{3}\right)^3\)

\(x+\frac{1}{3}=\frac{-2}{3}\)

\(x=-1\)

b) \(\left(\frac{1}{3}x+\frac{4}{3}\right)^2=\frac{25}{9}\)

\(\left(\frac{1}{3}x+\frac{4}{3}\right)^2=\left(\frac{5}{3}\right)^2\)

\(\frac{1}{3}x+\frac{4}{3}=\frac{5}{3}\)

\(\frac{1}{3}x=\frac{1}{3}\)

\(x=1\)

c) \(2^x+2^{x+1}=24\)

\(2^x+2^x.2=24\)

\(2^x.\left(1+2\right)=24\)

\(2^x.3=24\)

\(2^x=8\)

\(2^x=2^3\)

\(x=3\)

16 tháng 7 2017

a, (x+1/3)^3 = -8/27

=>(x+1/3)^3 = (-2/3)^3

=>x+1/3     = -2/3

=>x           = -1

b, (1/3x+4/3)^2 = 25/9

=>(1/3x+4/3)^2 = (5/3)^2

=>(1/3x+4/3)   = 5/3

=>1/3x           = 1/3

=>    x           = 1

c, 2^x + 2^x+1 = 24

=>2^x + 2^x . 2 = 24

=>2^x.(1+2)     = 24

=>2^x . 3         = 24

=>2^x              =8

=>2^x             = 2^3

=>  x              = 3

17 tháng 7 2016

a.

\(\left(x+\frac{1}{2}\right)\times\left(x-\frac{3}{4}\right)=0\)

TH1:

\(x+\frac{1}{2}=0\)

\(x=-\frac{1}{2}\)

TH2:

\(x-\frac{3}{4}=0\)

\(x=\frac{3}{4}\)

Vậy \(x=-\frac{1}{2}\) hoặc \(x=\frac{3}{4}\)

b.

\(\left(\frac{1}{2}x-3\right)\times\left(\frac{2}{3}x+\frac{1}{2}\right)=0\)

TH1:

\(\frac{1}{2}x-3=0\)

\(\frac{1}{2}x=3\)

\(x=3\div\frac{1}{2}\)

\(x=3\times2\)

\(x=6\)

TH2:

\(\frac{2}{3}x+\frac{1}{2}=0\)

\(\frac{2}{3}x=-\frac{1}{2}\)

\(x=-\frac{1}{2}\div\frac{2}{3}\)

\(x=-\frac{1}{2}\times\frac{3}{2}\)

\(x=-\frac{3}{4}\)

Vậy \(x=6\) hoặc \(x=-\frac{3}{4}\)

c.

\(\frac{2}{3}-\frac{1}{3}\times\left(x-\frac{3}{2}\right)-\frac{1}{2}\times\left(2x+1\right)=5\)

\(\frac{2}{3}-\frac{1}{3}x+\frac{1}{2}-x-\frac{1}{2}=5\)

\(\left(\frac{1}{2}-\frac{1}{2}\right)-\left(\frac{1}{3}x+x\right)=5-\frac{2}{3}\)

\(-\frac{4}{3}x=\frac{13}{3}\)

\(x=\frac{13}{3}\div\left(-\frac{4}{3}\right)\)

\(x=\frac{13}{3}\times\left(-\frac{3}{4}\right)\)

\(x=-\frac{13}{4}\)

d.

\(4x-\left(x+\frac{1}{2}\right)=2x-\left(\frac{1}{2}-5\right)\)

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

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

\(x=5\)

2 tháng 12 2018

a) 3/4+ 1/4:x = 2/5

1/4:x = 3/4-2/5

1/4:x= 7/20

x= 7/20:1/4

x= 7/5

b) chưa học

c) 15/8-1/8: (x/4 - 0,5) = 5/4

1/8: (x/4 -1/2)= 15/8-5/4

1/8:( x/4 -1/2) =  5/8

x/4 - 1/2 = 1/8:5/8

x/4 -1/2= 1/5

x/4= 1/5+1/2

x/4 = 7/7

x/4= 7/7× 4/4

x/4= 28/28

4/4=28/28

phần c ko chắc chắn

đúng k nhé

23 tháng 9 2017

1) \(\left|x-\frac{3}{5}\right|< \frac{1}{3}\)

\(\Rightarrow\orbr{\begin{cases}x-\frac{3}{5}< \frac{1}{3}\\x-\frac{3}{5}< -\frac{1}{3}\end{cases}}\Rightarrow\orbr{\begin{cases}x< \frac{1}{3}+\frac{3}{5}\\x< \frac{-1}{3}+\frac{3}{5}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x< \frac{5}{15}+\frac{9}{15}\\x< \frac{-5}{15}+\frac{9}{15}\end{cases}}\Rightarrow\orbr{\begin{cases}x< \frac{14}{15}\\x< \frac{4}{15}\end{cases}}\)

                vay \(\orbr{\begin{cases}x< \frac{14}{15}\\x< \frac{4}{15}\end{cases}}\)

2) \(\left|x+\frac{11}{2}\right|>\left|-5,5\right|\)

\(\left|x+\frac{11}{2}\right|>5,5\)

\(\Rightarrow\orbr{\begin{cases}x+\frac{11}{2}>\frac{11}{2}\\x+\frac{11}{2}>-\frac{11}{2}\end{cases}}\Rightarrow\orbr{\begin{cases}x>\frac{11}{2}-\frac{11}{2}\\x>\frac{-11}{2}-\frac{11}{2}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x>0\\x>-11\end{cases}}\)

vay \(\orbr{\begin{cases}x>0\\x>-11\end{cases}}\)

3) \(\frac{2}{5}< \left|x-\frac{7}{5}\right|< \frac{3}{5}\)

\(\Rightarrow\left|x-\frac{7}{5}\right|>\frac{2}{5}\) va \(\left|x-\frac{7}{5}\right|< \frac{3}{5}\)

\(\Rightarrow\orbr{\begin{cases}x-\frac{7}{5}>\frac{2}{5}\\x-\frac{7}{5}>\frac{-2}{5}\end{cases}}\Rightarrow\orbr{\begin{cases}x>\frac{2}{5}+\frac{7}{5}\\x>\frac{-2}{5}+\frac{7}{5}\end{cases}}\)va \(\orbr{\begin{cases}x-\frac{7}{5}< \frac{3}{5}\\x-\frac{7}{5}< \frac{-3}{5}\end{cases}}\Rightarrow\orbr{\begin{cases}x< \frac{3}{5}+\frac{7}{5}\\x< \frac{-3}{5}+\frac{7}{5}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x>\frac{9}{5}\\x>1\end{cases}}\)va \(\orbr{\begin{cases}x< 2\\x< \frac{4}{5}\end{cases}}\)

vay ....

28 tháng 12 2016

có 2 ý hả bạn

28 tháng 12 2016

có 2 ý thì mik giải dc