有理数的加减法..(1)(-8)+10+2+(-1)(2)5+(-6)+3+9+(-4)+(-7)(3)(-0.8)+1.2+(-0.7)+(2.1)+0.8+3.5(4)1/2+(-3/2)+5/4+(-1/2)+(-1/3)(5)(+3/5)+(-7/12)(6)(-3又2/3)+(-1/6)(7)(-0.25)+(+3/4)(8)(+1.579)+(-0.874
有理数的加减法..
(1)(-8)+10+2+(-1)
(2)5+(-6)+3+9+(-4)+(-7)
(3)(-0.8)+1.2+(-0.7)+(2.1)+0.8+3.5
(4)1/2+(-3/2)+5/4+(-1/2)+(-1/3)
(5)(+3/5)+(-7/12)
(6)(-3又2/3)+(-1/6)
(7)(-0.25)+(+3/4)
(8)(+1.579)+(-0.874)
(9)1+(-1/2)+(-1/3)
(10)(-1/5)+0(+8/15)
(11)(+7)+(-21)+(-7)+(+23)
(12)12+(-8)+11+(-2)+(-12)
如果a、b互为相反数,则a+2a+…+…+2009a+2009b+2008b+…+b=_______