用数学归纳法证明f（x）=1+12+13+14+…+12n-1>n2（n∈N*）的过程中，假设当n=k时成立，则当n=k+1时，左边f（k+1）=（）A.f（k）+12k+1-1B.f（k）+12k+1C.f（k）+12k-1+12k+12k+1+…+12k+1-1D.f（k）+12k+

Question

用数学归纳法证明f（x）=1+

(1)/(2)+(1)/(3)+(1)/(4)+…+(1)/(2n-1)>(n)/(2)（n∈N^*）的过程中，假设当n=k时成立，则当n=k+1时，左边f（k+1）=（　　）

A. f（k）+

(1)/(2k+1-1)

B. f（k）+

(1)/(2k+1)

C. f（k）+

(1)/(2k-1)+(1)/(2k)+(1)/(2k+1)+…+(1)/(2k+1-1)

D. f（k）+

(1)/(2k)+(1)/(2k+1)+…+(1)/(2k+1-1)

Answer 1

n=k时，f（k）=1+(1)/(2)+(1)/(3)+(1)/(4)+…+(1)/(2k-1)，
当n=k+1时，f（k+1）=1+(1)/(2)+(1)/(3)+(1)/(4)+…+(1)/(2k-1)+(1)/(2k)+(1)/(2k+1)+…+(1)/(2k+1-1)，
=f（k）+(1)/(2k)+(1)/(2k+1)+…+(1)/(2k+1-1)．
故选D．