x加1分之1加（x的平方减2x减3分之x的平方减x）除（x减3分之x）

网友回答

1/(X+1)+[(X^2-X)/(X^2-2X-3)]/(X/X-3)
=1/(X+1)+{[X(X-1)]/[(X-3)(X+1)]}/(X/X-3)
=1/(X+1)+(X-1)/(X+1)
=X/(X+1)