3, - 6,9, - 12 ··, - 20042007, - 2010 the 100th number is? The sum of this column is?

3, - 6,9, - 12 ··, - 20042007, - 2010 the 100th number is? The sum of this column is?

Regardless of the sign, the original sequence becomes 3, 6, 9, 12 , 2004, 2007, 2010 this is an arithmetic sequence, the first term is 3, the tolerance is 3, so A100 = 3 + 99 * 3 = 100 * 3 = 300, odd term is positive, even term is negative, so the sum of the 100th number is - 300 sequence = (3-6) + (9-12) + +(2001-2004)+(2...