(x^2+2x-8)/(x^3+2x^2+x)/{(x-2)/x .(x+4)/(x+1) 其中x=4/5

(x^2+2x-8)/(x^3+2x^2+x)/{(x-2)/x .(x+4)/(x+1) 其中x=4/5

(x^2+2x-8)/(x^3+2x^2+x)/{(x-2)/x .(x+4)/(x+1) =(x+4)(x-2)/[x(x+1)^2]/{(x+4)(x-2)/[x(x+1)]}=1/[x(x+1)^2]/{1/[x(x+1)]}=1/[x(x+1)^2][x(x+1)]=1/(x+1)=1/(1+4/5)=5/9