x-2x+3x-4x+.-2008x+2009x=?
问题描述:
x-2x+3x-4x+.-2008x+2009x=?
答
x-2x+3x-4x+.-2008x+2009x=x+3x-2x+5x-4x+.+2009x-2008x=1005x
x-2x+3x-4x+.-2008x+2009x=?
x-2x+3x-4x+.-2008x+2009x=x+3x-2x+5x-4x+.+2009x-2008x=1005x