Question

1,若x属于C,且|i i减1,x i+1|=0(i为虚数单位)则x=?2,计算：lim下面为n到无穷(1+2+2^2+

Answer 1

(1)是不是[i(i-1)]^2 + [x(i+1)]^2 = 0

如果是,2i + 2ix^2 = 0

x^2 = -1

x = ±i

(2)lim(n-->∞)[(1+2+2^2+...+2^(n-1)]/2^n = lim(n-->∞)[1*(1-2^n)/(1-2)]/2^n = lim(n-->∞)(2^n - 1)/2^n = 1