Đáp án: $x=-100$
Giải thích các bước giải:
$\dfrac{x+1}{99}+\dfrac{x+2}{98}=\dfrac{x+3}{97}+\dfrac{x+4}{96}$
$\rightarrow (\dfrac{x+1}{99}+1)+(\dfrac{x+2}{98}+1)=(\dfrac{x+3}{97}+1)+(\dfrac{x+4}{96}+1)$
$\rightarrow \dfrac{x+100}{99}+\dfrac{x+100}{98}=\dfrac{x+100}{97}+\dfrac{x+100}{96}$
$\rightarrow x+100=0$
$\rightarrow x=-100$