f(x)=(x^2-5x+6)/(x^2+1)の導関数を求めます~

f(x)=(x^2-5x+6)/(x^2+1)の導関数を求めます~

f(x)
=1+(-5x+5)/(x^2+1)
f'(x)=0+[-5(x^2+1)-2x(-5x+5)]/(x^2+1)
=5(x^2-2x-1)/(x^2+1)