Điền dấu (< , > , =) thích hợp vào chỗ (...) : A. \(\Large\dfrac{11}{1

Điền dấu (< , > , =) thích hợp vào chỗ (...) :

A. \(\Large\dfrac{11}{10} + \Large\dfrac{12}{11}+\Large\dfrac{13}{12}+...+\Large\dfrac{30}{29} \) ... \(\Large20\dfrac{2}{3}\)

B. \(\Large\dfrac{11}{10} + \Large\dfrac{12}{11}+\Large\dfrac{13}{12}+...+\Large\dfrac{30}{29} \) ... \(\Large\ 22\)

• A. A. >
• B. B. <

Đặt M =\(\Large\ {11 \over 10} + \Large\ {12 \over 11}+\Large\ {13 \over 12}+...+\Large\ {30 \over 29} \)

M = \(\Large\ 1{1 \over 10} + \Large\ 1{1 \over 11} +\Large\ 1{1 \over 12} +...+\Large\ 1{1 \over 29} \) ( có 20 hỗn số )

M = 1 x 20 + \(\Large\ {1 \over 10} + \Large\ {1 \over 11}+\Large\ {1 \over 12}+...+\Large\ {1 \over 29} \)

M > 20 + 20 x \(\Large\ {1 \over 30} \) = 20 + \(\Large\ {2 \over 3} \) = \(\Large\ 20{2 \over 3}\)

M =\(\Large\ {11 \over 10} + \Large\ {12 \over 11}+\Large\ {13 \over 12}+...+\Large\ {30 \over 29} \) 

M = 1 x 20 + \(\Large\ {1 \over 10} + \Large\ {1 \over 11}+\Large\ {1 \over 12}+...+\Large\ {1 \over 29} \)

M < 20 + 20 x \(\Large\ {1 \over 10} \) = 22

Đáp số: A: >

             B: <