Register Now

Login

Lost Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: Chứng tỏ rằng: 1/41+1/41+1/43+…+1/80>5/8

Toán Lớp 6: Chứng tỏ rằng: 1/41+1/41+1/43+…+1/80>5/8

Comments ( 2 )

  1. Lời giải và giải thích chi tiết:
    Gọi 1/41+1/42+1/43+…+1/80 là A. Ta có:
    A=(1/41+1/42+1/43+…+1/50)+(1/51+1/52+1/53+…+1/60)+(1/61+1/62+…+1/70)+(1/71+1/72+…+1/80)
    A>(1/50+1/50+…+1/50)+(1/60+1/60+…+1/60)+(1/70+1/70+…+1/70)+(1/80+1/80+…+1/80)
    A>1/5+1/3+2/7+1/4
    A>449/420
    Mà 449/420>350/420=5/6
     

Leave a reply

222-9+11+12:2*14+14 = ? ( )