计算（X²-2X分之X+2-X-2分之X-1)÷X分之X+3,并求当X=3时原式的值

计算（X²-2X分之X+2-X-2分之X-1)÷X分之X+3,并求当X=3时原式的值
计算（X²-2X分之X+2-X-2分之X-1)÷X分之X+3,并求当X=3时原式的值

计算（X²-2X分之X+2-X-2分之X-1)÷X分之X+3,并求当X=3时原式的值
{[(x+2)/(x^2-2x)]-[(x-1)/(x-2)]}/[(x+3)/x]
={[(x+2)/(x^2-2x)]-[(x^2-x)/(x^2-2x)]}*[x/(x+3)]
=[(-x^2+2x+2)/(x^2-2x)]/[(x+3)/x]
=(-x^2+2x+2)/(x^2+x-6)
将x=3代入得：-1/6