Question

Chứng tỏ rằng: 1/101+1/102+1/103+......+1/200 > 1/2

Answer 1

đặtA=1/101+1/102+1/103+...+1/200<1/200x100

                                             =1/2

=>A<1/2

Answer 2

Ta có: 1/101 > 1/200

1/102 > 1/200

1/103 > 1/200

........

1/199 > 1/200

1/200 = 1/200

=>1/101 +1/102 +1/103 +.... +1/199 +1/200 > 1/200 + 1/200 +1/200 +..... +1/200

=>1/101 + 1/102 +1/103 +..... +1/200 > 1/200x100 = 1/2

Vậy biểu thức đã cho > 1/2