a)

1/3 + 5/8 = 8/24 + 15/24 = 23/24

5/2 + 2/5 = 25/10 + 4/10 = 29/10

3/8 + 2/3 = 9/24 + 16/24 = 25/24

2/3 + 4/9 = 6/9 + 4/9 = 10/9

b)

1/4 + 2/3 = 3/12 + 8/12 = 11/12

3/5 + 5/6 = 18/30 + 25/30 = 43/30

4/6 + 5/7 = 2/3 + 5/7 = 14/21 + 15/21 = 29/21

7/9 + 8/9 = 15/9 = 5/3

c)

2/3 + 7/6 = 4/6 + 7/6 = 11/6

8/3 + 3/7 = 56/21 + 9/21 = 65/21

9/4 + 11/6 = 27/12 + 22/12 = 49/12

8/5 + 1/3 = 24/15 + 5/15 = 29/15

a)

1/3 + 5/8 = 8/24 + 15/24 = 23/24

5/2 + 2/5 = 25/10 + 4/10 = 29/10

3/8 + 2/3 = 9/24 + 16/24 = 25/24

2/3 + 4/9 = 6/9 + 4/9 = 10/9

b)

1/4 + 2/3 = 3/12 + 8/12 = 11/12

3/5 + 5/6 = 18/30 + 25/30 = 43/30

4/6 + 5/7 = 2/3 + 5/7 = 14/21 + 15/21 = 29/21

7/9 + 8/9 = 15/9 = 5/3

c)

2/3 + 7/6 = 4/6 + 7/6 = 11/6

8/3 + 3/7 = 56/21 + 9/21 = 65/21

9/4 + 11/6 = 27/12 + 22/12 = 49/12

8/5 + 1/3 = 24/15 + 5/15 = 29/15

đừng nói ninja rùa:D

36

ô :)

chx

hi

me

Ta có:

(2^2 + 4^2 + ... + 50^2) − (1^2 + 3^2 + ... + 49^2)

= (2^2 − 1^2) + (4^2 − 3^2) + ... + (50^2 − 49^2)

= (2 − 1)(2 + 1) + (4 − 3)(4 + 3) + ... + (50 − 49)(50 + 49)

= 3 + 7 + 11 + ... + 99

Dãy có số số hạng là:

(99 − 3) : 4 + 1 = 25

Tổng là:

(3 + 99) × 25 : 2 = 1275

Đáp số: 1275

chx tổ chức nhé bn