`7/(12) + x/(15) = 1/(20)`
`=> x/(15) = 1/(20) - 7/(12)`
`=> x /(15) = -8/(15)`
`=> x =-8`
Vậy `x =-8`
`7/(12) + x/(15) = 1/(20)`
`=> x/(15) = 1/(20) - 7/(12)`
`=> x /(15) = -8/(15)`
`=> x =-8`
Vậy `x =-8`
Tìm x ϵ Z, biết:
\(\dfrac{5}{17}\)+\(\dfrac{-4}{9}\)+-\(\dfrac{20}{31}\)+\(\dfrac{12}{17}\)+\(\dfrac{-11}{-31}\)< \(\dfrac{x}{9}\) ≤ \(\dfrac{-3}{7}\)+\(\dfrac{7}{15}\)+\(\dfrac{4}{-7}\)+\(\dfrac{8}{15}\)+\(\dfrac{2}{3}\)
Tìm x, biết:
a) \(\dfrac{3}{4}x\) - \(\dfrac{7}{12}\) = \(\dfrac{5}{6}\) - \(\dfrac{2}{3}\)
b) -\(\dfrac{5}{x}\) = \(\dfrac{20}{28}\)
c) \(2\dfrac{1}{3}\) : x = 7
d) \(\dfrac{-105}{12}\) < x < \(\dfrac{20}{7}\)
\(\dfrac{-7}{x}\)+\(\dfrac{8}{15}\)=\(\dfrac{-1}{20}\) Tìm x
Bài 2: Tìm x, biết:
a) \(x+\dfrac{-7}{15}=-1\dfrac{1}{20}\)
b) \(\left(3\dfrac{1}{2}-x\right).1\dfrac{1}{4}=-1\dfrac{1}{20}\)
7.Cho biết \(\dfrac{15}{x}=\dfrac{-3}{4}\) số x thích hợp là:
A. 20 B. -20 C. 63 D. 57
8.Tìm phân số tối giản trong các phân số sau:
A. \(\dfrac{6}{12}\) B. \(\dfrac{4}{16}\) C.\(\dfrac{-3}{4}\) D.\(\dfrac{15}{20}\)
Tìm x:
d) \(\dfrac{-5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)
e) \(\dfrac{x+3}{-15}=\dfrac{1}{3}\)
f) \(\left(4,5-2x\right).\left(-1\dfrac{4}{7}\right)=\dfrac{11}{14}\)
tìm x :
a, x . \(\dfrac{-5}{8}\) = \(\dfrac{15}{32}\) b, \(\dfrac{3}{10}\) : x =\(\dfrac{-9}{20}\)
c, \(\dfrac{-1}{4}\) x + \(\dfrac{4}{5}\) =\(\dfrac{3}{4}\) d, \(\dfrac{-7}{8}\) + \(\dfrac{2}{3}\) :x = \(\dfrac{3}{5}\) . \(\dfrac{-5}{12}\)
Tìm các số nguyên x,y biết:
a)\(\dfrac{6}{2x+1}=\dfrac{2}{7}\)
b) \(\dfrac{24}{7x-3}=\dfrac{-4}{25}\)
c) \(\dfrac{4}{x-6}=\dfrac{y}{24}=\dfrac{-12}{18}\)
d) \(\dfrac{-1}{5}\le\dfrac{x}{8}\le\dfrac{1}{4}\)
e) \(\dfrac{x+46}{20}=x\dfrac{2}{5}\)
f) \(y\dfrac{5}{y}=\dfrac{86}{y}\) ( \(x\dfrac{2}{5};y\dfrac{5}{y}\) là các hỗn số)
1.Thực hiện phép tính
a) \(\dfrac{4}{5}\) + \(\dfrac{6}{5}\) : \(\dfrac{7}{15}\) - \(\dfrac{3}{7}\)
b) \(\dfrac{9}{13}\) . \(\dfrac{5}{3}\) + \(\dfrac{-6}{13}\) .\(\dfrac{9}{13}\) - \(\dfrac{9}{13}\) . \(\dfrac{20}{13}\)
2.Tìm x,biết:
a) \(\dfrac{2}{5}\) . x - \(\dfrac{1}{3}\) = 1\(\dfrac{2}{3}\)
b) \(\dfrac{4}{9}\) - \(\dfrac{5}{9}\) : x = \(\dfrac{7}{3}\)
c) \(\dfrac{4}{5}\) . x + \(\dfrac{-7}{3}\) . x = \(\dfrac{\left(-2\right)^3}{5}\)
Tìm số nguyên x , y biết :
a) \(\dfrac{x}{15}=\dfrac{17}{51}\) b) \(\dfrac{-7}{y}=\dfrac{12}{24}\)
C2. Tìm tập hợp các phân số bằng phân số :
a) \(\dfrac{5}{12}\) b) \(\dfrac{2323}{2424}\)
C3. Một lớp có 43 HS nữ . Hỏi số nữ bằng mấy phần số nam .
C4. Rút gọn các phân số sau :
a) \(\dfrac{2.7.13}{26.35}\) b) \(\dfrac{23.5-23}{4-27}\) c) \(\dfrac{2130-15}{3550-25}\)