How do you differentiate f(x)=x/(x^2-1-sinx) using the quotient rule?

$f ' \left(x\right) = \frac{x \cos \left(x\right) - {x}^{2} - 1 - \sin \left(x\right)}{{x}^{2} - 1 - \sin \left(x\right)} ^ 2$
$f ' \left(x\right) = \frac{{x}^{2} - 1 - \sin \left(x\right) - x \left(2 x - \cos \left(x\right)\right)}{{x}^{2} - 1 - \sin \left(x\right)} ^ 2$
$f ' \left(x\right) = \frac{x \cos \left(x\right) - {x}^{2} - 1 - \sin \left(x\right)}{{x}^{2} - 1 - \sin \left(x\right)} ^ 2$