f=(x-2)^(-2)
f'=-2(x-2)^(-3)
f"=3!(x-2)^(-4)
..
f'n=(-1)^n*(n+1)!(x-2)^(-n-2)
f'n(0)=(-1)^n* (n+1)!(-2)^(-n-2)=(n+1)!/2^(n+1)
f(x)=1/4+2!/2^3 x+3!/2!2^4x^2+4!/3!2^5x^3.
=1/4+(2/2^3)x+(3/2^4) x^2+(4/2^5) x^3+...+[(n+1)/2^(n+2)] x^n+...
收敛区间为：-2