Lavander_tháng_Mộta)
[imath]Đkxđ : x\neq \pm6 ; x\neq 0[/imath]
[imath]S=(\dfrac{x}{x^2-36}-\dfrac{x-6}{x^2-6x}):\dfrac{2x-6}{x^2+6x}+\dfrac{x}{6-x}[/imath]
[imath]=(\dfrac{x}{(x-6)(x+6)}-\dfrac{x-6}{x(x+6)}):\dfrac{2x-6}{x(x+6)}-\dfrac{x}{x-6}[/imath]
[imath]=\dfrac{x^2-(x-6)^2}{x(x-6)(x+6)}.\dfrac{x(x+6)}{2x-6}-\dfrac{x}{x-6}[/imath]
[imath]=\dfrac{6}{x-6}-\dfrac{x}{x-6}=-1[/imath]
b) c) ?
ra đkxđ b nhé