当A=-3时,A-2A+3A-4A+``````+99A-100A的值是多少?当A=-3时,A-2A+3A-4A+````````````+99A-100A的值是多少?

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当A=-3时,A-2A+3A-4A+``````+99A-100A的值是多少?当A=-3时,A-2A+3A-4A+````````````+99A-100A的值是多少?当A=-3时,A-2A+3A-4

当A=-3时,A-2A+3A-4A+``````+99A-100A的值是多少?当A=-3时,A-2A+3A-4A+````````````+99A-100A的值是多少?
当A=-3时,A-2A+3A-4A+``````+99A-100A的值是多少?
当A=-3时,A-2A+3A-4A+````````````+99A-100A的值是多少?

当A=-3时,A-2A+3A-4A+``````+99A-100A的值是多少?当A=-3时,A-2A+3A-4A+````````````+99A-100A的值是多少?
数学题怎么放这里来了?…… 这题解法是这样的: 首先,不管A 1-2+3-4+……+99-100=(1+3+5+……+99)-(0+2+4+6+……100) 1+99=100 3+97=100 0+100=100 2+98=100以此类推 这上述结果就是-50A.得到答案150 或者另一种算法 1+(-2+3)+(-4+5)+……+(-98+99)-100=? 100/2=50,除去头尾,那括号应该有49个,也就是说有49个1,那就是1+49-100=-50 完毕~
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