Tìm x :

a) \(2.x.\frac{-3}{4}=-\frac{5}{12}\)

\(\Rightarrow2x=-\frac{5}{12}:-\frac{3}{4}\)

\(\Rightarrow2x=\frac{5}{9}\)

\(\Rightarrow x=\frac{5}{9}:2\)

\(\Rightarrow x=\frac{5}{18}\)

Vậy : \(x=\frac{5}{18}\)

b) \(\frac{2}{3}+\frac{1}{3}.x=7\)

\(\Rightarrow\frac{1}{3}.x=7-\frac{2}{3}\)

\(\Rightarrow\frac{1}{3}.x=\frac{19}{3}\)

\(\Rightarrow x=\frac{19}{3}:\frac{1}{3}\)

\(\Rightarrow x=19\)

Vậy : \(x=19\)

c) \(\left(4.x+\frac{1}{8}\right)=\frac{3}{10}\)

\(\Rightarrow4.x=\frac{3}{10}-\frac{1}{8}\)

\(\Rightarrow4.x=\frac{7}{40}\)

\(\Rightarrow x=\frac{7}{40}:4\)

\(\Rightarrow x=\frac{7}{160}\)

Vậy : \(x=\frac{7}{160}\)

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

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

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

\(\Rightarrow\frac{1}{3}.x=\frac{13}{2}\)

\(\Rightarrow x=\frac{13}{2}:\frac{1}{3}\)

\(\Rightarrow x=\frac{39}{2}\)

Vậy : \(x=\frac{39}{2}\)

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

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

\(\Rightarrow-\frac{2}{3}.x=-\frac{5}{6}\)

\(\Rightarrow x=-\frac{5}{6}:\left(-\frac{2}{3}\right)\)

\(\Rightarrow x=\frac{5}{4}\)

Vậy : \(x=\frac{5}{4}\)

a, -5/6 -x = 7/12 + -1/3
⇔-10/12 - 12x/12 = 7/12 + -4/12
⇒-10 - 12x = 7 - 4
⇔-12x = 7 - 4 +10
⇔-12x = 13
⇔x = -13/12
b, x+13/-15 = 1/3
⇔-(x+13)/15 = 5/15
⇒ -x - 13 = 5
⇔-x = 5 +13
⇔-x = 18
⇔x = -18
c,-15/x-1 = -3/5
⇔-75/(x-1).5 = -3.(x-1)/5.(x-1)
⇒-75 = -3x + 3
⇔3x = 3 + 75
⇔3x = 78
⇔x = 26
d, (1/2).x + -2/5 = 1/5
⇔5x/10 + -4/10 = 1/10
⇒5x - 4 = 1
⇔5x = 1 + 4
⇔5x = 5
⇔x = 1
e, (-2/3).x + 1/5 = 1/10
⇔-20x/30 + 6/30 = 3/30
⇒-20x + 6 = 3
⇔-20x = 3 - 6
⇔-20x = -3
⇔x = 3/20
f, 4/5 - (1/2).x = 1/10
⇔8/10 - 5x/10 = 1/10
⇒8 - 5x = 1
⇔-5x = 1 - 8
⇔-5x = -7
⇔x=7/5

a)\(\left(4\frac{5}{37}-3\frac45+8\frac{15}{29}\right)-\left(3\frac{5}{57}-6\frac{14}{29}\right)\)

=\(4\frac{5}{37}-3\frac45+8\frac{15}{29}-3\frac{5}{37}+6\frac{14}{29}\)

=\(\left(4\frac{5}{37}-3\frac{5}{37}\right)+\left(8\frac{15}{29}+6\frac{14}{29}\right)-3\frac45\)

=\(\left\lbrack\left(4-3\right)+\left(\frac{5}{37}-\frac{5}{37}\right)\right\rbrack+\left\lbrack\left(8+6\right)+\left(\frac{15}{29}\right.\right.\)+\(\frac{14}{29})\) -\(\frac{19}{5}\)

=\(1+0+14+1-\frac{19}{5}\)

=\(15+1-\frac{19}{5}\)

=\(16-\frac{19}{5}\)

=\(\frac{80}{5}-\frac{19}{5}\)

=\(\frac{61}{5}\)

a) \(2x-\frac{2}{3}-7x=\frac{3}{2}-1\\ 2x-7x-\frac{2}{3}=\frac{1}{2}\\ -5x=\frac{1}{2}+\frac{2}{3}\\ -5x=\frac{7}{6}\\ x=\frac{7}{6}:\left(-5\right)\\ x=\frac{-7}{30}\)Vậy \(x=\frac{-7}{30}\)

b) \(\frac{3}{2}x-\frac{2}{5}=\frac{1}{3}x-\frac{1}{4}\\ \frac{3}{2}x-\frac{1}{3}x=\frac{2}{5}-\frac{1}{4}\\ \frac{7}{6}x=\frac{3}{20}\\ x=\frac{3}{20}:\frac{7}{6}\\ x=\frac{9}{70}\)Vậy \(x=\frac{9}{70}\)

c) \(\frac{2}{3}-\frac{5}{3}x=\frac{7}{10}x+\frac{5}{6}\\ \frac{2}{3}-\frac{5}{6}=\frac{7}{10}x+\frac{5}{3}x\\ \frac{-1}{6}=\frac{71}{30}x\\ x=\frac{-1}{6}:\frac{71}{30}\\ x=\frac{-5}{71}\)Vậy \(x=\frac{-5}{71}\)

d) \(2x-\frac{1}{4}=\frac{5}{6}-\frac{1}{2}x\\ 2x+\frac{1}{2}x=\frac{5}{6}+\frac{1}{4}\\ \frac{5}{2}x=\frac{13}{12}\\ x=\frac{13}{12}:\frac{5}{2}\\ x=\frac{13}{30}\)Vậy \(x=\frac{13}{30}\)

e) \(3x-\frac{5}{3}=x-\frac{1}{4}\\ 3x-x=\frac{5}{3}-\frac{1}{4}\\ 2x=\frac{17}{12}\\ x=\frac{17}{12}:2\\ x=\frac{17}{24}\)Vậy \(x=\frac{17}{24}\)

Èo, chăm thế? Chăm hơn cả mik cơ, gần 11 h rồi onl thì thấy bài được bạn HISI làm hết rồi :((

a) \(\frac{2}{5}+\left(\frac{3}{4}-\frac{7}{10}\right)\)

\(=\frac{2}{5}+\frac{1}{20}\)

\(=\frac{9}{20}\)

b) \(\frac{-1}{8}-\left(\frac{2}{3}-\frac{11}{12}\right)\)

\(=-\frac{1}{8}-\left(-\frac{1}{4}\right)\)

\(=\frac{1}{8}\)

c) \(\frac{7}{5}-\left(\frac{1}{6}+\frac{9}{10}\right)\)

\(=\frac{7}{5}-\frac{16}{15}\)

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

d) \(\frac{2}{3}+\left(-\frac{1}{4}\right)+\frac{7}{12}-\left(-\frac{1}{4}\right)-\frac{5}{6}\)

\(=\left(\frac{2}{3}+\frac{7}{12}-\frac{5}{6}\right)+\left(-\frac{1}{4}+\frac{1}{4}\right)\)

\(=\left(\frac{5}{4}-\frac{5}{6}\right)+0\)

\(=\frac{5}{12}\)

e) \(2-\left\{\frac{1}{2}-\left[2-\left(\frac{1}{2}+2\right)-\frac{1}{2}\right]+2\right\}\)

\(=2-\left[\frac{1}{2}-\left(2-\frac{5}{2}-\frac{1}{2}\right)+2\right]\)

\(=2-\left[\frac{1}{2}-\left(-1\right)+2\right]\)

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

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

a) \(\frac{7}{5}.\frac{-31}{125}.\frac{1}{2}.\frac{10}{17}.\frac{-1}{2^3}=\frac{7.\left(-31\right).1.10.\left(-1\right)}{5.2.125.17.2^3}=\frac{31.7}{17.125.2^3}=\frac{217}{17000}\)

b) \(\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{20}{31}\right).\left(\frac{-5}{12}+\frac{1}{4}+\frac{1}{6}\right)=\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{20}{31}\right).0=0\)

c) \(\left(\frac{1}{2}+1\right).\left(\frac{1}{3}+1\right).\left(\frac{1}{4}+1\right)...\left(\frac{1}{99}+1\right)=\frac{3}{2}.\frac{4}{3}.\frac{5}{4}...\frac{100}{99}=\frac{3.4.5...100}{2.3.4...99}=\frac{100}{2}=50\)

d) \(\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)\left(\frac{1}{4}-1\right)...\left(\frac{1}{100}-1\right)=\frac{-1}{2}.\frac{-2}{3}.\frac{-3}{4}...\frac{-99}{100}=\frac{-\left(1.2.3..99\right)}{2.3.4...100}=-\frac{1}{100}\)

e) \(\frac{3}{2^2}.\frac{8}{3^2}.\frac{15}{4^2}...\frac{899}{30^2}=\frac{1.3}{2.2}.\frac{2.4}{3.3}.\frac{3.5}{4.4}...\frac{29.31}{30.30}=\frac{1.3.2.4.3.5...29.31}{2.2.3.3.4.4...30.30}=\frac{\left(1.2.3..29\right).\left(3.4.5...31\right)}{\left(2.3.4...30\right).\left(2.3.4...30\right)}\)

\(=\frac{1.31}{30.2}=\frac{31}{60}\)

1+³⁺⁴⁺⁹⁼

Ta có : \(A=\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right).......\left(1-\frac{1}{2017}\right)\)

\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}......\frac{2016}{2017}\)

\(=\frac{1.2.3......2016}{2.3.4.......2017}\)

\(=\frac{1}{2017}\)

\(\frac{x}{5}=\frac23\)

\(x\) = \(\frac23\times5\)

\(x=\frac{10}{3}\)

Vậy \(x=\frac{10}{3}\)

\(\frac{x}{3}-\frac12=\frac15\)

\(\frac{x}{3}\) = \(\frac15\) + \(\frac12\)

\(\frac{x}{3}\) = \(\frac{2}{10}+\frac{5}{10}\)

\(\frac{x}{3}=\frac{7}{10}\)

\(x=\frac{7}{10}\times3\)

\(x=\frac{21}{10}\)

Vậy \(x=\frac{21}{10}\)

\(\frac{x}{5}+\frac12=\frac{6}{10}\)

\(\frac{x}{5}=\frac{6}{10}-\frac12\)

\(\frac{x}{5}=\frac{6}{10}-\frac{5}{10}\)

\(\frac{x}{5}=\frac{1}{10}\)

\(x=\frac{1}{10}\times5\)

\(x=\frac12\)

Vậy \(x=\frac12\)

\(\frac{x+3}{15}\) = \(\frac13\)

\(x+3=\frac13\times15\)

\(x+3=5\)

\(x=5-3\)

\(x=2\)

Vậy \(x=2\)

a)\(\left(\frac38+\frac{-3}{4}+\frac{7}{12}\right):\frac56+\frac12\)

=\(\left(\frac{9}{24}+\frac{-18}{24}+\frac{14}{24}\right)\times\frac65+\frac12\)

=\(\frac{5}{24}\times\frac65+\frac12\)

=\(\frac14+\frac12\)

=\(\frac14+\frac24\)

=\(\frac34\)

b)\(\frac12+\frac34-\left(\frac34-\frac45\right)\)

=\(\frac12+\frac34-\frac34+\frac45\)

=\(\left(\frac12+\frac45\right)+\left(\frac34-\frac34\right)\)

=\(\left(\frac{5}{10}+\frac{8}{10}\right)+0\)

=\(\frac{13}{10}\)