22 tháng 8 2023 lúc 8:48
Bài 2:
a) \(A=\left(\dfrac{x}{x-1}-\dfrac{1}{x^2-x}\right):\dfrac{1}{x-1}\)
\(A=\left[\dfrac{x}{x-1}-\dfrac{1}{x\left(x-1\right)}\right]:\dfrac{1}{x-1}\)
\(A=\left[\dfrac{x^2}{x\left(x-1\right)}-\dfrac{1}{x\left(x-1\right)}\right]\cdot\left(x-1\right)\)
\(A=\dfrac{\left(x+1\right)\left(x-1\right)}{x\left(x-1\right)}\cdot\left(x-1\right)\)
\(A=\dfrac{\left(x+1\right)\left(x-1\right)}{x}\)
\(A=\dfrac{x^2-1}{x}\)
b) Thay \(x=-\dfrac{2}{3}\) vào A ta có:
\(A=\dfrac{\left(-\dfrac{2}{3}\right)^2-1}{-\dfrac{2}{3}}=\dfrac{5}{6}\)
c) Mình nhìn không rõ
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