1/x-1-1/x+1-2/x^2+1-4/x^4+1-8/x^8+1..=(x+1-x+1)/(x²-1）-2/（x²+1)-4/(x⁴+1)-8/(x^8+1)...=(2x²+2-2x²+2)/(x⁴-1)-4/(x⁴+1)-8/(x^8+1)=(4x⁴+4-4x⁴+4)/(x^8-1)-...