1^2-2^2+3^2-4^2+5^2-...-98^2+99^2-100^2+101^2
请根据(n+1)^2-n^2=n+(n+1)的规律来计算!(n大于等于1)
(实在不行也可以用其他的办法!)
人气:333 ℃ 时间:2019-10-09 10:11:51
解答
1^2-2^2+3^2-4^2+5^2-...-98^2+99^2-100^2+101^2
=1+(2+3)+(4+5)+(6+7).+(100+101)
=(1+100)+(2+99).+(50+51)+101
=101*51
=51511+(2+3)+(4+5)+(6+7).....+(100+101)请问这一步是怎么算的呢??(-2^2+3^2 )(-4^2+5^2)
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