f(x)=(x-1)2^x=2(x-1)2^(x-1)=2(x-1)2^(x-1)=2(x-1)e^[(x-1)ln2] = 2(x-1)∑[(x-1)ln2]^n/n!= ∑[2(ln2)^n/n!](x-1)^(n+1) .
