Đặt [tex]f'(2017)=g'(2017)=h'(2017)=a[/tex]
[tex]\Rightarrow \frac{g'(f+1)-f'(g+3)}{(f+1)^2}=a\Rightarrow \frac{a(f+1)-a(g+3)}{(f+1)^2}=a[/tex] [tex]\Rightarrow f-g-2=(f+1)^2[/tex]
[tex]\Rightarrow g=-f^2-f-3=-\left ( f+\frac{1}{2} \right )^2-\frac{11}{4}\leq \frac{-11}{4}[/tex]
Đáp án A thì phải