Bài 4: Tìm các cặp x, y sao cho: a) \(\dfrac{x}{3}\)-\(\dfra...

\(\dfrac{x}{3}\)-\(\dfra...">

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HG

Hoàng Gia Hân

9 tháng 5 2018

Bài 4: Tìm các cặp x, y sao cho:

a) \(\dfrac{x}{3}\)-\(\dfrac{4}{y}\)=\(\dfrac{1}{5}\)

b) \(\dfrac{5}{x-1}\)-\(\dfrac{y-1}{3}\)=\(\dfrac{1}{6}\)

#Hỏi cộng đồng OLM #Toán lớp 6

2

LP

Lê Phạm Phương Uyên

9 tháng 5 2018

https://i.imgur.com/OYB8niJ.jpg

LP

Lê Phạm Phương Uyên

9 tháng 5 2018

https://i.imgur.com/bPBxy42.jpg

Các câu hỏi dưới đây có thể giống với câu hỏi trên

DT

dương trà my

11 tháng 7 2017

tìm các số nguyên x, y biết a, \(\dfrac{24}{7x-3}\)=\(\dfrac{-4}{25}\) b, \(\dfrac{4}{x-6}\)=\(\dfrac{y}{24}\)=\(\dfrac{-12}{18}\) c, \(\dfrac{-1}{5}\)<\(\dfrac{x}{8}\)<\(\dfrac{1}{4}\) d, \(\dfrac{x+46}{20}\)=x\(\dfrac{2}{5}\) f, y\(\dfrac{5}{y}\)=\(\dfrac{86}{y}\) ...

#Hỏi cộng đồng OLM #Toán lớp 6

1

DT

dương trà my

11 tháng 7 2017

giúp zới

ND

Nguyễn Đa Tiến

30 tháng 3 2018

tìm x biết a) \(\dfrac{2}{3}\): x - \(\dfrac{5}{6}\)= 1\(\dfrac{1}{2}\) b) (\(\dfrac{5}{6}\) . x + \(\dfrac{2}{3}\)) : (\(\dfrac{2}{5}\) +\(1\dfrac{1}{3}\) )\(\dfrac{4}{9}\) c) \(|\)x - \(\dfrac{4}{3}\)\(|\) - \(\dfrac{5}{6}\) = \(\dfrac{3}{5}\) . \(1\dfrac{1}{2}\) d) \(|\)2x + \(\dfrac{1}{2}\)\(|\) - \(\dfrac{3}{4}\)=\(3\dfrac{1}{2}\) e) \(|\dfrac{3}{2}\)x - \(\dfrac{5}{6}|\)+ \(\dfrac{12}{5}\)=...

#Hỏi cộng đồng OLM #Toán lớp 6

1

ND

Nguyễn Đa Tiến

30 tháng 3 2018

các bạn ơi giúp mìh với mìh đag cần gấp ai nhanh và đúng thì mih tick cho

PT

Phạm Thanh Thảo

18 tháng 4 2017

Dạng 2: Tìm x Bài 1: Tìm x biết: a) \(\dfrac{x-1}{9}\) = \(\dfrac{8}{3}\) b) (\(\dfrac{3x}{7}+1\)) : (-4) = \(\dfrac{-1}{8}\) c) x + \(\dfrac{7}{12}\) = \(\dfrac{17}{18}-\) \(\dfrac{1}{9}\) d) 0,5x - \(\dfrac{2}{3}x\) = \(\dfrac{7}{12}\) e) \(\dfrac{29}{30}-\) (\(\dfrac{13}{23}+x\)) = \(\dfrac{7}{46}\) f) (x + \(\dfrac{1}{4}-\dfrac{1}{3}\)) : (2 + \(\dfrac{1}{6}-\dfrac{1}{4}\)) =\(\dfrac{7}{46}\) g)...

#Hỏi cộng đồng OLM #Toán lớp 6

1

MV

Mới vô

2 tháng 5 2017

Bài 1:

a)

\(\dfrac{x-1}{9}=\dfrac{8}{3}\\ \Leftrightarrow\dfrac{x-1}{9}=\dfrac{24}{9}\\ \Leftrightarrow x-1=24\\ x=24+1\\ x=25\)

b)

\(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{8}\\ \dfrac{3x}{7}+1=\dfrac{-1}{8}\cdot\left(-4\right)\\ \dfrac{3x}{7}+1=\dfrac{1}{2}\\ \dfrac{3x}{7}=\dfrac{1}{2}-1\\ \dfrac{3x}{7}=\dfrac{-1}{2}\\ 3x=\dfrac{-1}{2}\cdot7\\ 3x=\dfrac{-7}{2}\\ x=\dfrac{-7}{2}:3\\ x=\dfrac{-7}{6}\)

c)

\(x+\dfrac{7}{12}=\dfrac{17}{18}-\dfrac{1}{9}\\ x+\dfrac{7}{12}=\dfrac{5}{6}\\ x=\dfrac{5}{6}-\dfrac{7}{12}\\ x=\dfrac{1}{4}\)

d)

\(0,5x-\dfrac{2}{3}x=\dfrac{7}{12}\\ \dfrac{1}{2}x-\dfrac{2}{3}x=\dfrac{7}{12}\\ x\cdot\left(\dfrac{1}{2}-\dfrac{2}{3}\right)=\dfrac{7}{12}\\ \dfrac{-1}{6}x=\dfrac{7}{12}\\ x=\dfrac{7}{12}:\dfrac{-1}{6}\\ x=\dfrac{-7}{2}\)

e)

\(\dfrac{29}{30}-\left(\dfrac{13}{23}+x\right)=\dfrac{7}{46}\\ \dfrac{29}{30}-\dfrac{13}{23}-x=\dfrac{7}{46}\\ \dfrac{277}{690}-x=\dfrac{7}{46}\\ x=\dfrac{277}{690}-\dfrac{7}{46}\\ x=\dfrac{86}{345}\)

f)

\(\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\left(2+\dfrac{1}{6}-\dfrac{1}{4}\right)=\dfrac{7}{46}\\ \left(x-\dfrac{1}{12}\right):\dfrac{23}{12}=\dfrac{7}{46}\\ x-\dfrac{1}{12}=\dfrac{7}{46}\cdot\dfrac{23}{12}\\ x-\dfrac{1}{12}=\dfrac{7}{24}\\ x=\dfrac{7}{24}+\dfrac{1}{12}\\ x=\dfrac{3}{8}\)

g)

\(\dfrac{13}{15}-\left(\dfrac{13}{21}+x\right)\cdot\dfrac{7}{12}=\dfrac{7}{10}\\ \left(\dfrac{13}{21}+x\right)\cdot\dfrac{7}{12}=\dfrac{13}{15}-\dfrac{7}{10}\\ \left(\dfrac{13}{21}+x\right)\cdot\dfrac{7}{12}=\dfrac{1}{6}\\ \dfrac{13}{21}+x=\dfrac{1}{6}:\dfrac{7}{12}\\ \dfrac{13}{21}+x=\dfrac{2}{7}\\ x=\dfrac{2}{7}-\dfrac{13}{21}\\ x=\dfrac{-1}{3}\)

h)

\(2\cdot\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|-\dfrac{3}{2}=\dfrac{1}{4}\\ 2\cdot\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{1}{4}+\dfrac{3}{2}\\ 2\cdot\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{7}{4}\\ \left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{7}{4}:2\\ \left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{7}{8}\Rightarrow\left[{}\begin{matrix}\dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{7}{8}\\\dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{-7}{8}\end{matrix}\right.\\ \dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{7}{8}\\ \dfrac{1}{2}x=\dfrac{7}{8}+\dfrac{1}{3}\\ \dfrac{1}{2}x=\dfrac{29}{24}\\ x=\dfrac{29}{24}:\dfrac{1}{2}\\ x=\dfrac{29}{12}\\ \dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{-7}{8}\\ \dfrac{1}{2}x=\dfrac{-7}{8}+\dfrac{1}{3}\\ \dfrac{1}{2}x=\dfrac{-13}{24}\\ x=\dfrac{-13}{24}:\dfrac{1}{2}\\ x=\dfrac{-13}{12}\)

i)

\(3\cdot\left(3x-\dfrac{1}{2}\right)^3+\dfrac{1}{9}=0\\ 3\cdot\left(3x-\dfrac{1}{2}\right)^3=0-\dfrac{1}{9}\\ 3\cdot\left(3x-\dfrac{1}{2}\right)^3=\dfrac{-1}{9}\\ \left(3x-\dfrac{1}{2}\right)^3=\dfrac{-1}{9}:3\\ \left(3x-\dfrac{1}{2}\right)^3=\dfrac{-1}{27}\\ \left(3x-\dfrac{1}{2}\right)^3=\left(\dfrac{-1}{3}\right)^3\\ \Leftrightarrow3x-\dfrac{1}{2}=\dfrac{-1}{3}\\ 3x=\dfrac{-1}{3}+\dfrac{1}{2}\\ 3x=\dfrac{1}{6}\\ x=\dfrac{1}{6}:3\\ x=\dfrac{1}{18}\)

VT

vũ tường vi

31 tháng 3 2017

bài 1 : tính a,\(\dfrac{-6}{11}\): (\(\dfrac{3}{5}.\)\(\dfrac{4}{11}\)) b, \(\dfrac{7}{12}\) + \(\dfrac{5}{12}\) : 6 - \(\dfrac{11}{36}\) c, ( \(\dfrac{4}{5}\) +\(\dfrac{1}{2}\) ) : ( \(\dfrac{3}{13}\)-\(\dfrac{8}{13}\)) d, ( \(\dfrac{2}{3}\) -\(\dfrac{1}{4}\) +\(\dfrac{5}{11}\) ) : ( \(\dfrac{8}{12}\) +1 - \(\dfrac{7}{11}\) ) bài 2 , tìm x, biết a, \(\dfrac{-2}{5}\). x +\(\dfrac{4}{3}\) = \(\dfrac{7}{3}\) b,\(\dfrac{9}{8}\)+\(\dfrac{3}{8}\)-x = 0,125 c,\(\dfrac{3}{4}\):...

#Hỏi cộng đồng OLM #Toán lớp 6

7

DH

Đừng Hỏi Tên Tôi

31 tháng 3 2017

a;\(\dfrac{-6}{11}\) : \(\dfrac{12}{55}\) = \(\dfrac{-5}{2}\)

b;\(\dfrac{7}{12}\) + \(\dfrac{5}{72}\) - \(\dfrac{11}{36}\) = \(\dfrac{47}{72}\) - \(\dfrac{11}{36}\) = \(\dfrac{25}{72}\)

c;\(\dfrac{13}{10}\) : \(\dfrac{-5}{13}\) = \(\dfrac{-169}{50}\)

d; {\(\dfrac{5}{12}\) + \(\dfrac{5}{11}\) } : { \(\dfrac{5}{3}\) -\(\dfrac{7}{11}\) } = \(\dfrac{115}{132}\) : \(\dfrac{34}{33}\) = \(\dfrac{115}{136}\)

lưu ý mk ko chép đầu bài

VT

vũ tường vi

31 tháng 3 2017

mình cần gấp lắm đến chiều mai là phải nộp rùi

giúp mình nha thanks cá bạn trước ko có tâm trạng mà cười nữa

0

0o0^^^Nhi^^^0o0

17 tháng 8 2017

Tìm x, y \(\in Z\) thỏa mãn:

a. \(\dfrac{x}{3}-\dfrac{1}{y}=\dfrac{1}{2}\)

b. \(\dfrac{4}{x}+\dfrac{y}{3}=\dfrac{1}{6}\)

c.\(\dfrac{5}{x}-\dfrac{1}{6}=\dfrac{y}{3}\)

#Hỏi cộng đồng OLM #Toán lớp 6

1

HA

Hoàng Anh Thư

17 tháng 8 2017

a,\(\dfrac{x}{3}-\dfrac{1}{y}=\dfrac{1}{2}\)

=> \(\dfrac{1}{y}=\dfrac{x}{3}-\dfrac{1}{2}=>\dfrac{1}{y}=\dfrac{2x-3}{6}\)

=> y(2x-3)=6.1=6

=> y và 2x-3 là Ư (6)= {+-1,+-2,+-3,+-6}

2x-3	-1	1	2	-2	3	-3	6	-6
x	1	2	2,5	1/2	3	0	9/2	-3/2
y	-6	6	3	-3	2	-2	1	-1

vậy (x;y)= .......................

b,c làm tương tự

chúc bn học tốt

0

0o0^^^Nhi^^^0o0

17 tháng 8 2017

bn k thể giải ra đc ak giải ra ik mk tick cho 3 tick

CV

Cute Vô Đối

25 tháng 7 2018

1. Tìm x, biết: a, \(1\dfrac{3}{5}\) + \(\dfrac{\dfrac{2}{7}+\dfrac{2}{17}+\dfrac{2}{37}}{\dfrac{5}{7}+\dfrac{5}{17}+\dfrac{5}{37}}\) . x = \(\dfrac{16}{5}\) b, (\(\dfrac{1}{24.25}\) + \(\dfrac{1}{25.26}\) + . . . + \(\dfrac{1}{39.40}\) ) . 120 + x. \(\dfrac{1}{3}\) = -4 c, \(\left|x-\dfrac{1}{3}\right|\) . 2 + \(\dfrac{4}{5}\) = 0,24 d, \(\dfrac{24}{7x-3}\) = \(\dfrac{-4}{25}\) e, ( 50% x + \(5\dfrac{1}{4}\) ) , \(\dfrac{-2}{3}\) = \(2\dfrac{5}{6}\) f, \(1\dfrac{1}{3}\) -...

#Hỏi cộng đồng OLM #Toán lớp 6

1

NL

Nguyễn Lê Phước Thịnh

23 tháng 8 2022

a: \(\Leftrightarrow\dfrac{8}{5}+\dfrac{2}{5}\cdot x=\dfrac{16}{5}\)

=>2/5x=8/5

=>x=4

b: \(\Leftrightarrow\left(\dfrac{1}{24}-\dfrac{1}{25}+\dfrac{1}{25}-\dfrac{1}{26}+...+\dfrac{1}{39}-\dfrac{1}{40}\right)\cdot120+\dfrac{1}{3}x=-4\)

\(\Leftrightarrow x\cdot\dfrac{1}{3}+2=-4\)

=>1/3x=-6

=>x=-18

c: =>2|x-1/3|=0,24-4/5=-0,56<0

DT

dương trà my

8 tháng 8 2017

tìm các cặp số nguyên (a,b) sao cho

a,(x-2).(y+3)=5

b,xy-6x-3y=7

c,\(\dfrac{a}{2}\)-\(\dfrac{1}{b}\)=\(\dfrac{3}{4}\)

d,\(\dfrac{a-5}{6}\)-\(\dfrac{1}{b-2}\)=\(\dfrac{1}{8}\)

#Hỏi cộng đồng OLM #Toán lớp 6

1

MS

Mashiro Shiina

8 tháng 8 2017

\(\left(x-2\right)\left(y+3\right)=5\)

\(\Rightarrow x-2;y+3\inƯ\left(5\right)\)

\(Ư\left(5\right)=\left\{\pm1;\pm5\right\}\)

Xét ước

\(xy-6x-3y=7\)

\(\Rightarrow xy-6x-3y+18=25\)

\(\Rightarrow x\left(y-6\right)-3\left(y-6\right)=25\)

\(\Rightarrow\left(x-3\right)\left(y-6\right)=25\)

Xét ước

\(\dfrac{a}{2}-\dfrac{1}{b}=\dfrac{3}{4}\)

\(\Rightarrow\dfrac{1}{b}=\dfrac{3}{4}+\dfrac{a}{2}\)

\(\Rightarrow\dfrac{1}{b}=\dfrac{3}{4}+\dfrac{2a}{4}\)

\(\Rightarrow\dfrac{1}{b}=\dfrac{3+2a}{4}\)

\(\Rightarrow b\left(3+2a\right)=4\)

Xét ước

BT

Bach Thi Anh Thu

2 tháng 4 2017

1. Tim x: a. \(\dfrac{x}{5}\) = \(\dfrac{5}{6}\) + \(\dfrac{-19}{30}\) b. \(\dfrac{-5}{6}\) \(-x\) = \(\dfrac{7}{12}\)\(-\) \(\dfrac{1}{3}\)\(\times\) \(x\) c.2016\(^{^{ }3}\) \(\times\)2016\(^{^{ }x}\) = 2016\(^{^{ }8}\) d. \((x+\dfrac{3}{4}):\dfrac{5}{2}=3^1_2\) e. (2,8 \(x\) \(-\) 2\(^5\)) : \(\dfrac{2}{3}=3^2\) f. \(\dfrac{4}{7}\times x-\dfrac{2}{3}=\dfrac{2}{5}\) g. \((\dfrac{3x}{7}+1):\left(-4\right)=\dfrac{-1}{28}\) 2. Thuc hien phep tinh: a....

#Hỏi cộng đồng OLM #Toán lớp 6

5

Q

Quìn

2 tháng 4 2017

1. Tìm \(x\):

a) \(\dfrac{x}{5}=\dfrac{5}{6}+\dfrac{-19}{30}\)

\(\dfrac{x}{5}=\dfrac{1}{5}\)

\(\Rightarrow x=1\)

b) \(\dfrac{-5}{6}-x=\dfrac{7}{12}-\dfrac{1}{3}.x\)

\(\dfrac{-5}{6}-\dfrac{7}{12}=x-\dfrac{1}{3}.x\)

\(x-\dfrac{1}{3}.x=\dfrac{-17}{12}\)

\(\dfrac{2}{3}.x=\dfrac{-17}{12}\)

\(x=\dfrac{-17}{12}:\dfrac{2}{3}\)

\(x=\dfrac{-17}{8}\)

c) \(2016^3.2016^x=2016^8\)

\(2016^x=2016^8:2016^3\)

\(2016^x=2016^{8-3}\)

\(2016^x=2016^5\)

\(\Rightarrow x=5\)

d) \(\left(x+\dfrac{3}{4}\right):\dfrac{5}{2}=3\dfrac{1}{2}\)

\(\left(x+\dfrac{3}{4}\right):\dfrac{5}{2}=\dfrac{7}{2}\)

\(\left(x+\dfrac{3}{4}\right)=\dfrac{7}{2}.\dfrac{5}{2}\)

\(x+\dfrac{3}{4}=\dfrac{35}{4}\)

\(x=\dfrac{35}{4}-\dfrac{3}{4}\)

\(x=\dfrac{32}{4}=8\)

e) \(\left(2,8.x-2^5\right):\dfrac{2}{3}=3^2\)

\(\left(2,8.x-2^5\right)=9.\dfrac{2}{3}\)

\(2,8.x-2^5=6\)

\(2,8.x=6+32\)

\(2,8.x=38\)

\(x=38:2,8\)

\(x=\dfrac{95}{7}\)

f) \(\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{2}{5}\)

\(\dfrac{4}{7}.x=\dfrac{2}{5}+\dfrac{2}{3}\)

\(\dfrac{4}{7}.x=\dfrac{16}{15}\)

\(x=\dfrac{16}{15}:\dfrac{4}{7}\)

\(x=\dfrac{28}{15}\)

g) \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)

\(\left(\dfrac{3x}{7}+1\right)=\dfrac{-1}{28}.\left(-4\right)\)

\(\dfrac{3x}{7}+1=\dfrac{1}{7}\)

\(\dfrac{3x}{7}=\dfrac{1}{7}-1\)

\(\dfrac{3x}{7}=\dfrac{-6}{7}\)

\(\Rightarrow3x=-6\)

\(x=\left(-6\right):3\)

\(x=-2\)

Q

Quìn

2 tháng 4 2017

2. Thực hiện phép tính:

a) \(\dfrac{1}{2}+\dfrac{1}{2}.\dfrac{2}{3}-\dfrac{1}{3}:\dfrac{3}{4}+1\dfrac{4}{5}\)

\(=\dfrac{1}{2}.\left(\dfrac{2}{3}+1\right)-\dfrac{1}{3}:\dfrac{3}{4}+\dfrac{9}{5}\)

\(=\dfrac{1}{2}.\dfrac{5}{3}-\dfrac{1}{3}:\dfrac{3}{4}+\dfrac{9}{5}\)

\(=\dfrac{5}{6}-\dfrac{4}{9}+\dfrac{9}{5}\)

\(=\dfrac{7}{18}+\dfrac{9}{5}\)

\(=\dfrac{197}{90}\)

b) \(\dfrac{7.5^2-7^2}{7.24+21}\)

\(=\dfrac{7.25-7.7}{7.24+7.3}\)

\(=\dfrac{7.\left(25-7\right)}{7.\left(24+3\right)}\)

\(=\dfrac{7.18}{7.27}\)

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

c) \(\dfrac{2}{3}+\dfrac{1}{3}.\left(\dfrac{-4}{9}+\dfrac{5}{6}\right):\dfrac{7}{12}\)

\(=\dfrac{2}{3}+\dfrac{1}{3}.\dfrac{7}{18}:\dfrac{7}{12}\)

\(=\dfrac{2}{3}+\dfrac{7}{54}:\dfrac{7}{12}\)

\(=\dfrac{2}{3}+\dfrac{2}{9}\)

\(=\dfrac{8}{9}\)

DV

Đặng Vũ Hoài Anh

4 tháng 8 2017

Bài 1: Tính ( hợp lý nếu có thể) A=\(\dfrac{-3}{8}\)+\(\dfrac{12}{25}\)+\(\dfrac{5}{-8}\)+\(\dfrac{2}{-5}\)+\(\dfrac{13}{25}\) B=\(\dfrac{-3}{15}\)+(\(\dfrac{2}{3}\)+\(\dfrac{3}{15}\)) C=\(\dfrac{-5}{21}\)+(\(\dfrac{-16}{21}\)+1) D=(\(\dfrac{-1}{6}\)+\(\dfrac{5}{-12}\))+\(\dfrac{7}{12}\) E=\(\dfrac{1}{3}\)x\(\dfrac{4}{5}\)+\(\dfrac{1}{3}\)x\(\dfrac{6}{5}\)+\(\dfrac{2}{3}\) F=\(\dfrac{-5}{6}\)x\(\dfrac{4}{19}\)+\(\dfrac{-7}{12}\)x\(\dfrac{4}{12}\)-\(\dfrac{40}{47}\) Bài 2: Tìm...

#Hỏi cộng đồng OLM #Toán lớp 6

2

CB

Cô Bé Yêu Đời

4 tháng 8 2017

Bài 1: Tính ( hợp lý nếu có thể )

\(A=\dfrac{-3}{8}+\dfrac{12}{25}+\dfrac{5}{-8}+\dfrac{2}{-5}+\dfrac{13}{25}\)

\(=\left(\dfrac{-3}{8}+\dfrac{5}{-8}\right)+\left(\dfrac{12}{25}+\dfrac{13}{25}\right)+\dfrac{2}{-5}\)

\(=-1+1+\dfrac{2}{-5}\)

\(=0+\dfrac{2}{-5}\)

\(=\dfrac{2}{-5}\)

\(B=\dfrac{-3}{15}+\left(\dfrac{2}{3}+\dfrac{3}{15}\right)\)

\(=\left(\dfrac{-3}{15}+\dfrac{3}{15}\right)+\dfrac{2}{3}\)

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

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

\(C=\dfrac{-5}{21}+\left(\dfrac{-16}{21}+1\right)\)

\(=\left(\dfrac{-5}{21}+\dfrac{-16}{21}\right)+1\)

\(=-1+1\)

\(=0\)

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

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

\(=\dfrac{1}{6}+\dfrac{-1}{6}\)

\(=0\)

CB

Cô Bé Yêu Đời

4 tháng 8 2017

Bài 2: Tìm x,biết:

a) \(x+\dfrac{2}{3}=\dfrac{4}{5}\)

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

\(x=\dfrac{2}{15}\)

Vậy \(x=\dfrac{2}{15}\)

b) \(x-\dfrac{2}{3}=\dfrac{7}{21}\)

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

\(x=\dfrac{1}{3}+\dfrac{2}{3}\)

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

Vậy \(x=1\)

c) sai đề hay sao ấy bạn.bỏ dấu - ở x thì đúng đề.mk giải luôn nha!

\(x-\dfrac{3}{4}=\dfrac{-8}{11}\)

\(x=\dfrac{-8}{11}+\dfrac{3}{4}\)

\(x=\dfrac{1}{44}\)

Vậy \(x=\dfrac{1}{44}\)

d) \(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\)

\(\dfrac{2}{5}+x=\dfrac{11}{12}-\dfrac{2}{3}\)

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

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

\(x=-\dfrac{3}{20}\)

Vậy \(x=-\dfrac{3}{20}\)