化简:a-2a+3a-4a+.+99a-100a怎么算

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化简:a-2a+3a-4a+.+99a-100a怎么算

化简:a-2a+3a-4a+.+99a-100a怎么算
化简:a-2a+3a-4a+.+99a-100a怎么算

化简:a-2a+3a-4a+.+99a-100a怎么算
a-2a+3a-4a+.+99a-100a
=(a-2a)+(3a-4a)+.+(99a-100a)
共50个括号,每个括号里面是-a
=-a*50
=-50a

-50a
(a-2a)+(3a-4a)+.....+(99a-100a)

a-2a=-a,3a-4a=-a,.....99a-100a=-a
a-2a+3a-4a+.....+99a-100a=-50a

a-2a+3a-4a+……+99a-100a=(a-2a)+(3a-4a)+……+(99a-100a)=-a*50=-50a

a-2a+3a-4a+.....+99a-100a
=a(1-2+3-4+....+99-100)
=a(-1-1-1-1...-1)
=-50a