\(\dfrac{7}{11}\)< x - \(\dfrac{1}{7}\)...">
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a: \(\dfrac{7}{11}< x-\dfrac{1}{7}< \dfrac{10}{13}\)

\(\Leftrightarrow\dfrac{7}{11}+\dfrac{1}{7}< x< \dfrac{10}{13}+\dfrac{1}{7}\)

hay 60/77<x<83/91

b: \(\dfrac{7}{9}< \dfrac{13}{11}-x< \dfrac{15}{16}\)

\(\Leftrightarrow\dfrac{-7}{9}>x-\dfrac{13}{11}>-\dfrac{15}{16}\)

\(\Leftrightarrow-\dfrac{7}{9}+\dfrac{13}{11}>x>\dfrac{-15}{16}+\dfrac{13}{11}\)

\(\Leftrightarrow\dfrac{40}{99}>x>\dfrac{43}{176}\)

a: \(\dfrac{x+2}{27}=\dfrac{x}{-9}\)

=>x+2=-3x

=>4x=-2

hay x=-1/2

b: \(\dfrac{-7}{x}=\dfrac{21}{34-x}\)

=>-7(34-x)=21x

=>34-x=-3x

=>2x=-34

hay x=-17

c: \(\dfrac{-8}{15}< \dfrac{x}{40}< \dfrac{-7}{15}\)

\(\Leftrightarrow-64< 3x< -56\)

hay \(x\in\left\{-21;-20;-19\right\}\)

d: \(\dfrac{-1}{2}< \dfrac{x}{18}< \dfrac{-1}{3}\)

=>-9<x<-6

hay \(x\in\left\{-8;-7\right\}\)

7 tháng 3 2017

bạn cứ tính 2 vế là xong mà:

a) x\(\in\){1;2;3;4;5;6;7}

b) x=0

5 tháng 3 2017

a) ta co:

1/18<x/12<y/9<1/4

=>2/36<x.3/36<y.4/36<9/36

=>x.3thuộc{3;6};y.4thuộc{4;8}

=>x thuộc{1;2};y thuộc{1:2}

b) ta co

7/8<x/40<9/10

=>70/80<x.2/40<72/80

=>x.2 =71

=>x=71/2

21 tháng 4 2017

tìm x a)
\(\dfrac{7}{2}\)-\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{4}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{4}\) + \(\dfrac{7}{2}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{12}+\dfrac{7}{12}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-12}{12}=1\)
\(x+\dfrac{7}{10}\)= 1 . \(\dfrac{6}{5}\)
*Rồi tự làm phần tt đi




20 tháng 4 2017

Mình ghi kết quả luôn nha bạn

a: \(\Leftrightarrow70+18< x< 120+126+70\)

=>88<x<316

hay \(x\in\left\{89;90;...;315\right\}\)

b: \(\Leftrightarrow-\dfrac{9}{3}< x< \dfrac{8}{5}+\dfrac{9}{5}=\dfrac{17}{5}\)

=>-3<x<3,4

hay \(x\in\left\{-2;-1;0;1;2;3\right\}\)

a: \(=\dfrac{-28}{36}+\dfrac{15}{36}-\dfrac{26}{36}=\dfrac{-39}{36}=\dfrac{-13}{12}\)

b: \(=\dfrac{11}{9}\left(\dfrac{15}{4}-\dfrac{7}{4}-\dfrac{5}{4}\right)=\dfrac{11}{9}\cdot\dfrac{3}{4}=\dfrac{11}{12}\)

c: \(=15+\dfrac{9}{7}+6+\dfrac{2}{3}-5-\dfrac{5}{9}\)

\(=16+\dfrac{88}{63}=\dfrac{1096}{63}\)

d: \(=\dfrac{5}{6}-\dfrac{1}{3}+\dfrac{2}{18}\)

\(=\dfrac{15-6+2}{18}=\dfrac{11}{18}\)

27 tháng 3 2017

A=\(\dfrac{2}{7}+\dfrac{-3}{8}+\dfrac{11}{7}+\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{5}{-3}\)

A=\(\left(\dfrac{2}{7}+\dfrac{11}{7}+\dfrac{1}{7}\right)+\left(\dfrac{1}{3}+\dfrac{5}{-3}\right)+\dfrac{-3}{8}\)

A=\(2+\dfrac{-4}{3}+\dfrac{-3}{8}\)

A=\(\dfrac{7}{24}\)

B=\(\dfrac{3}{17}+\dfrac{-5}{13}+\dfrac{-18}{35}+\dfrac{14}{17}+\dfrac{17}{-35}+\dfrac{-8}{13}\)

B=\(\left(\dfrac{3}{17}+\dfrac{14}{17}\right)+\left(\dfrac{-18}{35}+\dfrac{17}{-35}\right)+\left(\dfrac{-5}{13}+\dfrac{-8}{13}\right)\)

B=\(\dfrac{17}{17}+\dfrac{-35}{35}+\dfrac{-13}{13}\)

B=\(1+\left(-1\right)+\left(-1\right)=-1\)

C=\(\dfrac{-3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)\)

C=\(\dfrac{-3}{17}+\dfrac{2}{3}+\dfrac{3}{17}=\left(\dfrac{-3}{17}+\dfrac{3}{17}\right)+\dfrac{2}{3}\)

C=0+\(\dfrac{2}{3}=\dfrac{2}{3}\)

D=\(\left(\dfrac{-1}{6}+\dfrac{5}{-12}\right)+\dfrac{7}{12}\)

D=\(\dfrac{-1}{6}+\dfrac{5}{-12}+\dfrac{7}{12}\)

D=\(\dfrac{-2}{12}+\dfrac{-5}{12}+\dfrac{7}{12}=\left(\dfrac{-2}{12}+\dfrac{-5}{12}\right)+\dfrac{7}{12}\)

D=\(\dfrac{-7}{12}+\dfrac{7}{12}=0\)

a: \(\Leftrightarrow-\dfrac{720}{150}=-4.8< x< \dfrac{-63}{210}=-0.3\)

mà x là số nguyên

nen \(x\in\left\{-4;-3;-2;-1\right\}\)

b: \(\Leftrightarrow-\dfrac{125}{27}< x< \dfrac{120}{210}=\dfrac{4}{7}\)

mà x là số nguyên

nên \(x\in\left\{-4;-3;-2;-1;0\right\}\)

27 tháng 7 2017

Các bạn ơi,mình ghi thiếu,còn 3 câu nữa nha!!!~~nya

e)| \(\dfrac{5}{2}\)x-\(\dfrac{1}{2}\) |-(-22).\(\dfrac{1}{3}\)(0,75-\(\dfrac{1}{7}\))=\(\dfrac{-5}{13}\):2\(\dfrac{9}{13}\)-0,5.(\(\dfrac{-2}{3}\))

f)| 5x+21 | = | 2x -63 |

g) -45 - |-3x-96 | - 54=-207

Làm ơn giúp mình với ạ!Mình đang cần gấp lắm trong ngày hôm nay ạ!!!Mình xin cảm ơn các bạn nhiều nhiều lắm luôn đó!!!Thank you very much!!!(^-^)

1 tháng 8 2017

a, (\(\dfrac{2}{9}\)(6x - \(\dfrac{3}{4}\)) - 3(\(\dfrac{1}{4}x-\dfrac{1}{5}\)) = \(\dfrac{-8}{15}\)

<=> (\(\dfrac{4}{3}x-\dfrac{1}{6}\)) - (\(\dfrac{3}{4}x-\dfrac{3}{5}\)) = \(\dfrac{-8}{15}\)

<=> \(\dfrac{4}{3}x-\dfrac{1}{6}-\dfrac{3}{4}x+\dfrac{3}{5}=\dfrac{-8}{15}\)

<=> \(\dfrac{7}{12}x+\dfrac{13}{30}=\dfrac{-8}{15}\)

<=> \(\dfrac{7}{12}x=\dfrac{-8}{15}-\dfrac{13}{30}\)

<=> \(\dfrac{7}{12}x=-\dfrac{29}{30}\)

<=> x = \(-\dfrac{58}{35}\)
@Nguyễn Gia Hân