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23 tháng 4 2018

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

\(x+\frac{2}{5}=\frac{7}{5}\)

\(\Rightarrow x=\frac{7}{5}-\frac{2}{5}\)

\(\Rightarrow x=\frac{5}{5}\)

\(\rightarrow x=1\)Vậy x = 1

23 tháng 4 2018

X=1

Học tốt nha!

^_^ @_@

a: \(\Leftrightarrow\left(\dfrac{13}{4}:x\right)\cdot\left(-\dfrac{5}{4}\right)=\dfrac{-10}{6}-\dfrac{5}{6}=\dfrac{-15}{6}=\dfrac{-5}{2}\)

\(\Leftrightarrow\dfrac{13}{4}:x=\dfrac{5}{2}\cdot\dfrac{5}{4}=\dfrac{25}{8}\)

hay \(x=\dfrac{13}{4}:\dfrac{25}{8}=\dfrac{13}{4}\cdot\dfrac{8}{25}=\dfrac{26}{25}\)

b: \(\Leftrightarrow\dfrac{3}{4}:x=\dfrac{11}{36}-\dfrac{1}{4}=\dfrac{2}{36}=\dfrac{1}{18}\)

=>\(x=\dfrac{3}{4}:\dfrac{1}{18}=\dfrac{54}{4}=\dfrac{27}{2}\)

c: \(\Leftrightarrow\left(-\dfrac{6}{5}+x\right):\left(-3.6\right)=-\dfrac{7}{4}+\dfrac{1}{4}\cdot8=\dfrac{1}{4}\)

=>x-6/5=-9/10

=>x=3/10

14 tháng 5 2017

1 a)38000             b)1/8                c)3/2          d)9/17

2  a) 0.64           b)0.025                 c)-1

14 tháng 5 2017

Bài giải:

Câu 1: a, \(\left(-2\right).4.5.38.\left(-25\right)\)

\(=\left[\left(-2\right).5\right].\left[4.\left(-25\right)\right].38\)

\(=\left(-10\right).\left(-100\right).38\)

\(=1000.38=38000\)

b,\(\frac{1}{3}+\frac{3}{8}-\frac{7}{12}\)

\(=\left(\frac{1}{3}+\frac{3}{8}\right)-\frac{7}{12}\)

\(=\frac{17}{24}-\frac{7}{12}=\frac{1}{8}\)

c, \(\frac{-5}{8}.\frac{5}{12}+\frac{-5}{8}.\frac{7}{12}+2\frac{1}{8}\)

\(=\frac{-5}{8}.\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{17}{8}\)

\(=\frac{-5}{8}.1+\frac{17}{8}\)

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

Câu 2: a, \(x-\frac{2}{5}=0,24\)

               \(x-0,4=0,24\)

               \(x=0,24+0,4\)

         \(\Rightarrow x=0,64\left(\frac{16}{25}\right)\)

b,\(\frac{2}{3}.x+\frac{1}{12}=\frac{1}{10}\)

\(\frac{2}{3}.x=\frac{1}{10}-\frac{1}{12}\)

\(\frac{2}{3}.x=\frac{1}{60}\)

       \(x=\frac{1}{60}:\frac{2}{3}\)

   \(\Rightarrow x=\frac{1}{40}\)

c, \(\left(3\frac{1}{2}-2x\right).1\frac{1}{3}=7\frac{1}{3}\)

\(\frac{7}{2}-2x=\frac{22}{3}:\frac{4}{3}\)

\(\frac{7}{2}-2x=\frac{11}{2}\)

            \(2x=\frac{7}{2}-\frac{11}{2}\)

             \(2x=-2\)

            \(\Rightarrow x=-2:2\)

                  \(x=-1\)

2 tháng 3 2018

\(1,4x\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):2\frac{1}{5}\)

\(=\frac{3}{7}-\frac{22}{15}:2\frac{1}{5}\)

\(=\frac{3}{7}-\frac{2}{3}=-\frac{5}{21}\)

học tốt ~~~

2 tháng 3 2018

\(1,4\times\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right)\div2\frac{1}{5}\)

\(=\frac{14}{10}\times\frac{15}{49}-\frac{22}{15}\div\frac{11}{5}\)

\(=\frac{7}{5}\times\frac{15}{49}-\frac{22\times5}{15\times11}\)

\(=\frac{7\times15}{5\times49}-\frac{22\times5}{15\times11}\)

\(=\frac{7\times7\times3\times5}{5\times7\times7}-\frac{11\times2\times5}{3\times5\times11}\)

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

\(=\frac{7}{3}\)

26 tháng 7 2020

\(\left(x-2\right):2.3=6\)

\(\Leftrightarrow\left(x-2\right):2=2\)

\(\Leftrightarrow\left(x-2\right)=4\)

\(\Leftrightarrow x=4+2=6\)

c) ta có

\(\left[\left(2x+1\right)+1\right]m:2=625\)

\(\Leftrightarrow\left[\left(2x+1\right)+1\right]\left\{\left[\left(2x+1\right)-1\right]:2+1\right\}=1250\)

\(\Leftrightarrow\left(2x+1\right)^2+1-1:2+1=1250\)

\(\Leftrightarrow\left(2x+1\right)^2+1-2+1=1250\)

\(\Leftrightarrow\left(2x+1\right)^2+1-2=1249\)

\(\Leftrightarrow\left(2x+1\right)^2+1=1251\)

\(\Leftrightarrow\left(2x+1\right)^2=1250\)

...

2

\(\left(x-\frac{1}{2}\right).\frac{5}{3}=\frac{7}{4}-\frac{1}{2}\)

\(\Leftrightarrow\left(x-\frac{1}{2}\right).\frac{5}{3}=\frac{5}{4}\)

\(\Leftrightarrow\left(x-\frac{1}{2}\right)=\frac{5}{4}:\frac{5}{3}\)

\(\Leftrightarrow\left(x-\frac{1}{2}\right)=\frac{5}{4}.\frac{3}{5}\)

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

\(\Leftrightarrow x=\frac{3}{4}+\frac{1}{2}=\frac{5}{4}\)

8 tháng 6 2021

\(\dfrac{x+46}{20}=x\dfrac{2}{5}\)

\(\Rightarrow\dfrac{x+46}{20}=\dfrac{5x+2}{5}\)

\(\Leftrightarrow5\cdot\left(x+46\right)=20\cdot\left(5x+2\right)\)

\(\Leftrightarrow100x+40-5x-230=0\)

\(\Leftrightarrow95x-190=0\)

\(\Leftrightarrow x=2\)

14 tháng 7 2020

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12 tháng 6 2018

Dài wa nên mk chỉ ghi đáp án thui nha

a, x=1

b,x=66

c,x=4

d,x=5/3

e,x=17/25

12 tháng 6 2018

ghi rõ ra cho mình ý b,d,e được ko

Bài 1:

\(a,\left(\frac{1}{2}\right)^{3x-1}=\frac{1}{32}\) 

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

\(\Rightarrow3x-1=5\)

\(\Rightarrow3x=6\)

\(\Rightarrow x=2\)

\(b,\frac{64}{\left(-2\right)^x}=-8\)

\(\Rightarrow\left(-2\right)^x=64:\left(-8\right)\)

\(\Rightarrow\left(-2\right)^x=-8\)

\(\Rightarrow\left(-2\right)^x=\left(-2\right)^3\)

\(\Rightarrow x=3\)

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

\(\Rightarrow-8+0,5x=1,5\)

\(\Rightarrow0,5x=9,5\)

\(\Rightarrow x=19\)

Bài 2,

\(a,\frac{3}{8}.27\frac{1}{5}-51\frac{1}{5}.\frac{3}{8}+19=\frac{3}{8}\left(27\frac{1}{5}-51\frac{1}{5}\right)+19\)

\(=\frac{3}{8}\left(-24\right)+19\)

\(=-9+19=10\)

\(b,25\left(-\frac{1}{5}\right)^3+\frac{1}{5}-2.\left(-\frac{1}{2}\right)^2-\frac{1}{2}=-\frac{1}{5}+\frac{1}{5}-\left(-\frac{1}{2}\right)-\frac{1}{2}\)

\(=0\)

\(c,35\frac{1}{6}:\left(-\frac{4}{5}\right)-45\frac{1}{6}:\left(-\frac{4}{5}\right)=-\frac{4}{5}\left(35\frac{1}{6}-45\frac{1}{6}\right)\)

\(=-\frac{4}{5}.\left(-10\right)=8\)

\(d,\left(-0,25\right).8,7.2^2=\left(-0,25\right).8,7.4\)

\(=-1.8,7=-8,7\)

\(e,13\frac{1}{3}.\frac{5}{8}-23\frac{1}{3}:\frac{8}{5}=\frac{40}{3}.\frac{5}{8}-\frac{70}{3}.\frac{5}{8}\)

\(=\frac{5}{8}\left(\frac{40}{3}-\frac{70}{3}\right)\)

\(=\frac{5}{8}.-10\)

\(=-\frac{25}{4}\)