1×(2×3)/(3×4)×(4×5)/(5×6)×...×(2008×2009)/(2009×2010)=? (注:/
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1×(2×3)/(3×4)×(4×5)/(5×6)×...×(2008×2009)/(2009×2010)=? (注:/=除号)
![1×(2×3)/(3×4)×(4×5)/(5×6)×...×(2008×2009)/(2009×2010)=? (注:/](/uploads/image/z/16149730-58-0.jpg?t=1%C3%97%282%C3%973%29%EF%BC%8F%283%C3%974%29%C3%97%284%C3%975%29%2F%285%C3%976%29%C3%97...%C3%97%282008%C3%972009%29%EF%BC%8F%282009%C3%972010%29%3D%3F+%28%E6%B3%A8%EF%BC%9A%EF%BC%8F)
你先等会 再答: 由方程(1)可知:(x-3y)(x+y)=0 ==>x=3y x=-y 当x=3y时,代入(2)可得:9y +6y=-2 ==>方程无解,即x≠3y 当x=-y时,代表(2)可得:y +6y=-2 ==>y=-3+√7 x=3-√7 或者y=-3-√7 x=3+√7
再答: 错了
再答: 等于 2/2010=1/1005
再答: 2/2010=1/1005
再答: 1*(2*3)/(3*4)*(4*5)/(5*6)*……*(2008*2009)/(2009*2010) (=1*2)*(3/3)*(4/4)*(5/5)*(6/6)*……*(2008/2008)*(2009/2009)*1/2010 =2/2010 =1/1005
再问: 1005分之1?
再答: 错了
再答: 等于 2/2010=1/1005
再答: 2/2010=1/1005
再答: 1*(2*3)/(3*4)*(4*5)/(5*6)*……*(2008*2009)/(2009*2010) (=1*2)*(3/3)*(4/4)*(5/5)*(6/6)*……*(2008/2008)*(2009/2009)*1/2010 =2/2010 =1/1005
再问: 1005分之1?
(1+3+5+...+2009)-(2+4+6+...+2008)=?
1-2+3-4+5-6+...+2007-2008-2009=
1-2-3+4+5-6-7+8+9-10-11+12+...+2008+2009-2010=
1-2-3+4+5-6-7+8+9-10+12+...+2008+2009-2010=
(2+4+6+.+2008+2010)-(1+3+5+.+2007+2009)=?
(2+4+6+.2010)—(1+3+5+.2009)=
1-2+3-4+5-6+.+2009-2010+2011=?
请问(2/2009+4/2009+6/2009+···+2008/2009)—(1/2009+3/2009+5/2009
.2-3+4-5+...+2008-2009+2010=
1-2+3-4+5-6.+2007-2008+2009-2010
(1)计算1+2+3+4+5-6+7+8+9+10...+2007+2008+2009+2010
计算 1-2+3-4+5-6+...+2003-2004+2005-2006+2007-2008+2009-2010+2