rút gọn c c = ( 1/x ² + 1 – x + 1/x ∧4 -1) : x+ 1/ x ∧5 + x ∧4 -x -1 ( ai có avatar anime đẹp tui cho hay nhất )

$\rm C=(\dfrac{1}{x^2+1}-\dfrac{x+1}{x^4-1}):\dfrac{x+1}{x^5+x^4-x-1} \\C=(\dfrac{1}{x^2+1}-\dfrac{x+1}{(x^2+1)(x^2-1)}):\dfrac{x+1}{x^5+x^4-x-1}\\C=(\dfrac{x^2-1-(x+1)}{(x^2+1)(x^2-1)}:\dfrac{x+1}{x^5+x^4-x-1}\\C=(\dfrac{x^2-x-2}{(x^2+1)(x^2-1)}):\dfrac{x+1}{(x+1)^2(x-1)(x^2+1)} \\C=(\dfrac{(x+1)(x-2)}{(x^2+1)(x-1)(x+1)}).\dfrac{(x+1)^2(x-1)(x^2+1)}{x+1}\\C=(x-2)(x-1)\\C=x^2-x-2\\ Vậy \ C=x^2-x-2\\\rm $