先化简,再求值;1/(x+1)-(x²+3x+2)/(x+1)×1/(x²-4),其中x=3

问题描述:

先化简,再求值;1/(x+1)-(x²+3x+2)/(x+1)×1/(x²-4),其中x=3

1/(X+1)-(x+2)(x+1)/(x+1)*1/[(x+2)(x-2)]=-3/[(x+1)(x-2)]
把x=3代入,原式=-3/4