If a, C, D are integers and B is a positive integer, and a + B = C, B + C = D, C + D = a is satisfied, then the maximum value of a + B + C + D is () A. -1B. -5C. 0D. 1

If a, C, D are integers and B is a positive integer, and a + B = C, B + C = D, C + D = a is satisfied, then the maximum value of a + B + C + D is () A. -1B. -5C. 0D. 1

∵ a + B = C, ∵ a = C-B, and ∵ B + C = D, C + D = a, a = C-B, ∵ C = - 2b, a = - 3b, d = - B, ∵ a + B + C + D = - 5b, ∵ B is a positive integer, its minimum value is 1, and the maximum value of ∵ a + B + C + D = - 5b is - 5

If a, C, D are integers and B is a positive integer, and a + B = C, B + C = D, C + D = a is satisfied, then the maximum value of a + B + C + D is ()
A. -1B. -5C. 0D. 1

∵ a + B = C, ∵ a = C-B, and ∵ B + C = D, C + D = a, a = C-B, ∵ C = - 2b, a = - 3b, d = - B, ∵ a + B + C + D = - 5b, ∵ B is a positive integer, its minimum value is 1, and the maximum value of ∵ a + B + C + D = - 5b is - 5

-4/9,10/9,4/3,7/9,1/9 A．7/3 B 10/9 C -5/18 D -2
-4/9,10/9,4/3,7/9,1/9
A．7/3 B 10/9 C -5/18 D -2

Because for positive integer n, 1 / [n * (n + 1) * (n + 2)] = [1 / (2n)] - [1 / (n + 1)] + {1 / [2 * (n + 2)]} primitive = (1 / 4) - (1 / 3) + (1 / 8) + (1 / 6) - (1 / 4) + (1 / 10) + (1 / 8) - (1 / 5) + (1 / 12) + (1 / 6) + (1 / 14) + (1 / 12) - (1 / 7) + (1 / 16) + (1 / 14) - (1 / 8) + (1 / 18) + (1 / 16) - (1 / 9)