Question

tính 1/2.5+1/5.8+1/8.11+....+1/92.95+1/95.98

mong các bạn giải gúi mình mình đang gấp

 

Answer 1

= 1/3.(1/2-1/5)+1/3.(1/5-1/8)+....+1/3.(1/92-1/95)+1/3.(1/95-1/98)

=1/3.(1/2-1/5+1/5-1/8+....+1/92-1/95+1/95-1/98)

=1/3.(1/2-1/98)

=1/3.24/49

=8/49

Answer 2

Phân tích: 1/2.5 = 1/2 - 1/5

1/5.8 = 1/5 - 1/8

1/8.11 = 1/8 - 1/11

...

1/92.95 = 1/92 - 1/95

1/95.98 = 1/95 - 1/98

Ta có: 1/2 - 1/5 + 1/5 - 1/8 + 1/8 - 1/11 +...+ 1/92 - 1/95 + 1/95 - 1/98

3 = 3/2.5 + 3/5.8 + 3/8.11 + ...+ 3/92.95 + 3/95.98

3 =  1 - 1/2 + 1/2 - 1/5 + 1/5 - 1/8 + 1/8 - 1/11 +...+ 1/92 - 1/95 + 1/95 - 1/98

= 1 - 1/98

= 97/98 : 3 = 97/98 x 1/3 = (tự tính)

Answer 3

1/2.5+...+1/95.98

=1/2-1/5+1/5-1/8+....1/95+1/98

=1/2-1/98

=24/49

K NHA!!!

Answer 4

1/2.5 = 1/3.(1/2-1/5)

1/5.8 = 1/3.(1/5-1/8)

\(⋮\)

1/95.98 = 1/3.(1/95-1/98)

=1/3.(1/2-1/98)=8/49

=> 1/2.5+1/5.8+1/8.11+...+1/92.95+1/95.98=8/49

Answer 5

k cho mình

Answer 6

chép y như của tth nhé,mình làm giống vậy đó

Nhãn

Answer 7

1/2.5+1/5.8+1/8.11+...+1/95.98

= 3/2.5+3/5.8+3/8.11+...+3/95.98

= 1/2-1/5+1/5-1/8+1/8-1/11+...+1/95-1/98

= 1/2-1/98

= 24/49

Answer 8

1/2.5+1/5.8+1/8.11+...+1/92.95+1/95.98

=1/3.(3/2-3/5+3/5-3/8+.........+3/92-3/95+3/95-3/98)

=1/3.(3/2-3/98)

=1/3.(147/98-3/98)

=1/3.144/98

=24/49

Answer 9

tự làm