Question

tính( rút gọn)

a)\(\dfrac{a}{9a-18}-\dfrac{b-1}{6b}-\dfrac{ab-3a+6}{9ab-18b}\)

b)\(\dfrac{x}{a-2}+\dfrac{2x-ax-a}{2a-a^2}-\dfrac{x}{a}\)

Answer 1

a: \(=\dfrac{a}{9\left(a-2\right)}-\dfrac{b-1}{6b}-\dfrac{ab-3a+6}{9b\left(a-2\right)}\)

\(=\dfrac{2ab}{18b\left(a-2\right)}-\dfrac{3\left(b-1\right)\left(a-2\right)}{18b\left(a-2\right)}-\dfrac{2ab-6a+12}{18b\left(a-2\right)}\)

\(=\dfrac{2ab-3\left(ba-2b-a+2\right)-2ab+6a-12}{18b\left(a-2\right)}\)

\(=\dfrac{6a-12-3ab+6b+3a-6}{18b\left(a-2\right)}\)

\(=\dfrac{3a+12b-3ab-18}{18b\left(a-2\right)}\)

\(=\dfrac{a+4b-ab-6}{6b\left(a-2\right)}\)

b: \(=\dfrac{xa-2x+ax+a-x\left(a-2\right)}{a\left(a-2\right)}\)

\(=\dfrac{2ax-2x+a-xa+2x}{a\left(a-2\right)}=\dfrac{xa+a}{a\left(a-2\right)}=\dfrac{x+1}{a-2}\)