y=1/(x^2-3x+2)展開成冪函數

y=1/(x^2-3x+2)展開成冪函數

y=1/(x-1)(x-2)=1/(x-2)-1/(x-1)=-0.5/(1-x/2)+1/(1-x)=-0.5[1+x/2+x^2/4+x^3/8+…]+[1+x+x^2+x^3+…]=(1/2)+(3/4)x+(7/8)x^2+…+(1-1/2^(n+1))x^n+…收斂域為|x|