来自韩慧莲的问题
化简a-2a+3a-4a+5a'''''''+99a-100aa=-2的值
化简a-2a+3a-4a+5a'''''''+99a-100aa=-2的值


化简a-2a+3a-4a+5a'''''''+99a-100aa=-2的值
化简a-2a+3a-4a+5a'''''''+99a-100aa=-2的值
a-2a+3a-4a+5a'''''''+99a-100a
=(a-2a)+(3a-4a)+(5a-6a)+……+(99a-100a)
=-a-a-a……-a共50个
=-50a
当a=-2时
原式=-50a=100