chứng tỏ rằng 14n+3/21n+5 là phân số tối giản với moi thuộc z

A=5^2/1.6+5^2/6.11+.....+5^2/26.31>1

1/20 +1/30 +1/42 +1/56+....+1/990

giải hộ mình nha

Put the verbs in to correct tense to finish the following passage

The tigers won the gold cup last week . They ( play) .........fewer matches than the Lions or the Leopards, but they(score) .... more points. In fact, the Tigers (lose ) ...only five matches during the season. The Zebras (beat ) ... the lion and (take ) .......second place. They (score ) .... 30 points from 22 matches . The Zebras( have) ....a very strong team . They (win ) .....a lot of matches and but not many teams (beat)... them . The Pandas(be)... at the bottom of the league . They lost most of their matches this season

mong các bạn giúp mình nhanh nhé

tính nhanh;

1.1/2. 1.1/3.1.1/4. ...1.1/999

tìm phân số a/b bằng phân số 18/27, biết UCLN (a,b) =13