1-[(x-1)/x]÷{[x/(x+2)] -[1/(x^2+2x)]}
＝(x-x+1)/x÷x/{(x+2) -1/[x(x+2)]}
＝1/x÷[(x-2)(x+2)/x(x+2)-1/x(x+2)]
＝1/x÷[x²-2²-1/x(x+2)]
＝1/x÷(x² -5)/x(x+2)
＝1/x×x(x+2)/(x² -5)
＝(x+2)/(x² -5)