Add: 1x+1x2+1x3\dfrac{1}{x} + \dfrac{1}{x^2} + \dfrac{1}{x^3}x1+x21+x31 (assume x≠0x \neq 0x=0).
x2+x+1x3\dfrac{x^2 + x + 1}{x^3}x3x2+x+1
3x6\dfrac{3}{x^6}x63
1+1+1x+x2+x3\dfrac{1 + 1 + 1}{x + x^2 + x^3}x+x2+x31+1+1
x+1x3\dfrac{x + 1}{x^3}x3x+1