(x+1)/(x²+3x+2)+(x²-2x)/(x²-4)

(x+1)/(x²+3x+2)+(x²-2x)/(x²-4)
(x+1)/(x²+3x+2)+(x²-2x)/(x²-4)

(x+1)/(x²+3x+2)+(x²-2x)/(x²-4)

对于两个分式，分母不为零所以x≠-1，±2。2(x+1)/(x²+3x+2)=(x+1)/(x+1)(x+2)=1/(x+2),
(x²-2x)/(x²-4)=x(x-2)/[(x-2)(x+2)]=x/(x+2)
所以和在一起(x+1)/(x²+3x+2)+(x²-2x)/(x²-4)=(x+1)/(x+2), x≠-1，±2