\(\dfrac{x+1}{x-3}=\dfrac{x+7}{x-2}\) ĐK : \(\left\{{}\begin{matrix}x-3\ne0\\x-2\ne0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x\ne3\\x\ne2\end{matrix}\right.\)
`=> (x+1)(x-2)=(x-3)(x+7)`
`=> x^2 -2x +x-2 = x^2+7x-3x-21`
`=> x^2 -x -2 = x^2+4x-21`
`=>x^2 -x-x^2-4x = -21+2`
`=> -5x = -19`
`=>x=19/5` (t/m)
tìm x, biết:
e) \(\dfrac{2}{7-x}\)=\(\dfrac{18}{45}\) f)\(\dfrac{2x+3}{3}\)=\(\dfrac{50}{15}\) g)\(2\dfrac{x}{7}\)=\(\dfrac{75}{35}\) h)\(2\dfrac{3}{x}\)=\(\dfrac{13}{x}\)(x khác 0)
Tìm \(x\), biết :
a) \(x=\dfrac{1}{4}+\dfrac{2}{13}\)
b) \(\dfrac{x}{3}=\dfrac{2}{3}+\dfrac{-1}{7}\)
\(\dfrac{x}{2}\)-(\(\dfrac{3x}{5}\)-\(\dfrac{13}{5}\))=-(\(\dfrac{7}{5}\)+\(\dfrac{7}{10}\).\(x\))
\(\dfrac{2x-3}{3}\)+\(\dfrac{-3}{2}\)=\(\dfrac{5-3x}{6}\)-\(\dfrac{1}{3}\)
\(\dfrac{2}{3x}\)-\(\dfrac{3}{12}\)=\(\dfrac{4}{5}-\left(\dfrac{7}{x}-2\right)\)
bài 45: Tìm x, biết:
a) x=\(\dfrac{-1}{2}+\dfrac{3}{4}\); b) \(\dfrac{x}{5}=\dfrac{5}{6}+\dfrac{-19}{30}\)
\(\dfrac{x+2}{7}\)=\(\dfrac{-36}{28}\)
tìm x:
\(\dfrac{-6}{7}+\dfrac{2}{5}< \dfrac{x}{5}< \dfrac{-3}{105}+\dfrac{17}{35}\)
Bài 1: \(\dfrac{x}{5}\)=\(\dfrac{100}{x}\) với x=0
Bài 2: Cho biểu thức A= \(\dfrac{x-7}{x+6}\)
a. Tìm điều kiện của cá số nguyên x để biểu thưc Alà phân số.
b. Tìm các số nguyên x để biểu thức A có giá trị là số nguyên
Bài 3:Cộng các phân số sau ( tính nhanh nếu có tích )
a) \(\dfrac{-6}{7}\)+\(\dfrac{5}{3}\) b) \(\dfrac{-9}{10}\)+\(\dfrac{5}{-9}\) c) \(\dfrac{6}{12}\)+\(\dfrac{-8}{22}\)
d) \(\dfrac{-7}{-15}\)+\(\dfrac{3}{-4}\) e) \(\dfrac{11}{24}\)+ ( \(\dfrac{-35}{24}\)+1)
tìm x biết \(\dfrac{-15}{41}+\dfrac{-138}{41}\le x\le\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{6}\)
\(Tìmxbiết\dfrac{1}{5.8}+\dfrac{1}{8.11}+\dfrac{1}{11.14}+...+\dfrac{1}{x+\left(x+3\right)}\)
