1. My sister can swim but she can't play badminton. 2. She goes to that French restaurant every week because she loves French food. 3. He stayed up late to watch a football match so he was tired last night. 4. I don't like this TV program because it's boring. 5. My mum and his mum went to Ho Chi Minh City last month.

chúc bạn học tốt=)))

C = 1 101 + 1 102 + ... + 1 200 C = ( 1 101 + 1 102 + ... + 1 120 ) + ( 1 121 + 1 122 + . . + 1 150 ) + ( 1 151 + 1 152 + … + 1 180 ) + ( 1 181 + 1 182 + ... + 1 200 ) C > 20 . 1 120 + 30 . 1 150 + 30 . 1 180 + 20 . 1 200 C > 1 6 + 1 5 + 1 6 + 1 10 C > ( 1 6 + 1 6 ) + ( 1 5 + 1 10 ) C > 1 3 + 3 10 C > 19 30 = 76 120 C > 75 120 + 1 120 C > 5 8 + 1 120 Vậy C > 5 8 còn lại giống trên

ta có:1/[n*(n+1)] = 1/n -1/(n+1) 1/2² + 1/3² + 1/4² +...+1/100² < 1/(2*3) +1/(3*4) +1/(4*5) + ... +1/(100*101) mà 1/(2*3) +1/(3*4) +1/(4*5) + ... +1/(100*101) =1/2 - 1/3 +1/3 -1/4 +....+1/100 - 1/101 =1/2 - 1/101 = 99/202<3/4 =>1/2² + 1/3² + 1/4² +...+1/100² < 3/4