Question

các bạn ơi giúp mk voi 

so sánh A va B biet

A=1/5x5+1/6x6+1/7x7+.....+1/99x99+1/100x100

b=1/6

ghi ra ca cach làm de hiểu nhất nhé!!!!!!!!!!!!!giúp vs mà mink tick cho may cai cung dc 10 lun

Answer 1

đặt A=1/5x5 +1/6x6 + 1/7x7 +  .....+ 1/100x100
    =>A>1/5x6 + 1/6x7 +1/7x8 + .... + 1/100x101
    =>A>1/5 - 1/6 + 1/6 - 1/7 + +1/7 - 1/8 + ..... + 1/100 - 1/101
    =>A> 1/5 - 1/101
    =>A>96/505 > 96/576 = 1/6
    =>A>1/6
    =>A>B

Answer 2

a>1/5x6+1/6x7+...+1/100x101

=1/5-1/6+1/6-1/7+...+1/100-1/101

=1/5-1/101

=101/505-5/101

=96/101

vì 96/101>1/6 nên a>1/6