1*-2*+3*-4*+5*-6*+…+2003*-2004*+2005*=?
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1*-2*+3*-4*+5*-6*+…+2003*-2004*+2005*=?
![1*-2*+3*-4*+5*-6*+…+2003*-2004*+2005*=?](/uploads/image/z/19994027-59-7.jpg?t=1%2A-2%2A%2B3%2A-4%2A%2B5%2A-6%2A%2B%E2%80%A6%2B2003%2A-2004%2A%2B2005%2A%3D%3F)
1*-2*+3*-4*+5*-6*+…+2003*-2004*+2005*
=1^2+(3^2-2^2)+(5^2-4^2)+.+(2005^2-2004^2)
=1^2+(3+2)(3-2)+(5+4)(5-4)+.+(2005+2004)(2005-2004)
=1^2+5+9+.+4009
=1^2+(5+4009)×[(4009-5)÷4+1]÷2
=1+2011014
=2011015
=1^2+(3^2-2^2)+(5^2-4^2)+.+(2005^2-2004^2)
=1^2+(3+2)(3-2)+(5+4)(5-4)+.+(2005+2004)(2005-2004)
=1^2+5+9+.+4009
=1^2+(5+4009)×[(4009-5)÷4+1]÷2
=1+2011014
=2011015
1-2+3-4+5-6+7-8+9-10+……2003-2004+2005=
(1+3+5+……+2001+2003+2005)—(2+4+6+……+2000+2002+2004)=
1+2-3-4+5+……+2001+2002-2003-2004+2005=
问一个数学题 1×1—2×2+3×3—4×4+5×5—6×6+……+2003×2003—2004×2004+2005×2
1-2+3-4+5-6…+2003-2004+2005-2006+2007的值是多少?
1+(-2)+(-3)+4+5+(-6)+(-7)+8+…+2001+(-2002)+(-2003)+2004+2005
1+2+3+…+2004+2005+2006= 1+3+5+…+2001+2003+2005+2007
(1+3+5+.2001+2003+2005)-(2+4+6+.2000+2002+2004)=?
1-2+3-4+5-6+...-2002+2003-2004+2005-2006+2007=?
(1+3+5+……+2003)-(2+4+6+……+2004)=
一,3-4+5-6+…+2003-2004+2005
2005+2004+2003……+3+2+1=?