Bài 4:
\(a,=\dfrac{4-x^2-2x+2x^2+5-4x}{x-3}=\dfrac{x^2-6x+9}{x-3}=\dfrac{\left(x-3\right)^2}{x-3}=x-3\\ b,=\dfrac{2x-4+4x+8-5x-2}{\left(x-2\right)\left(x+2\right)}=\dfrac{x+2}{\left(x-2\right)\left(x+2\right)}=\dfrac{1}{x-2}\\ c,=\dfrac{y^2-x^2}{xy\left(x-y\right)}=\dfrac{-\left(x-y\right)\left(x+y\right)}{xy\left(x-y\right)}=\dfrac{-x-y}{xy}\\ d,=\dfrac{x-y-2x-x-y}{x\left(x+y\right)\left(x-y\right)}=\dfrac{-2\left(x+y\right)}{x\left(x-y\right)\left(x+y\right)}=\dfrac{-2}{x\left(x-y\right)}\)
Bài 2:
\(a,\dfrac{1}{x-2};\dfrac{2}{2x-4}=\dfrac{2}{2\left(x-2\right)}=\dfrac{1}{x-2};\dfrac{3}{3x-6}=\dfrac{3}{3\left(x-2\right)}=\dfrac{1}{x-2}\\ b,PT\left(1\right)=\dfrac{2\left(x-4\right)}{2\left(x+4\right)\left(x-4\right)};PT\left(2\right)=\dfrac{x-4}{2\left(x+4\right)\left(x-4\right)}\\ PT\left(3\right)=\dfrac{6\left(x+4\right)}{2\left(x-4\right)\left(x+4\right)}\\ c,PT\left(1\right)=\dfrac{1}{\left(x-1\right)\left(x+1\right)};PT\left(2\right)=\dfrac{2\left(x+1\right)}{\left(x-1\right)\left(x+1\right)}\\ PT\left(3\right)=\dfrac{2\left(x-1\right)}{\left(x-1\right)\left(x+1\right)}\)
Bài 3:
\(a,=\dfrac{2x-4+3x+14}{5}=\dfrac{5\left(x+2\right)}{5}=x+2\\ b,=\dfrac{x+1+x-18+x+2}{x-5}=\dfrac{3\left(x-5\right)}{x-5}=3\\ c,=\dfrac{12+3x}{2x\left(x+4\right)}=\dfrac{3\left(x+4\right)}{2x\left(x+4\right)}=\dfrac{3}{2x}\)
