1x2+2x4+3x6+.+1005x2010
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1x2+2x4+3x6+.+1005x2010
1x2+2x4+3x6+.+1005x2010
1x2+2x4+3x6+.+1005x2010
上边那个算错了
1x2+2x4+3x6+.+1005x2010
= (1^2)x(1x2) + (2^2)x(1x2) + (3^2)x(1x2) + ...+ (1005^2)x(1x2)
= (1^2+2^2+3^2+...+1005^2)×2
= 1005(1005+1)(2×1005+1)/6 × 2
= 4066362600
关于怎么计算“1^2+2^2+3^2+……+n^2"的值可以看百度知道里这个帖子
1x2+2x4+3x6+.+1005x2010
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1x2+2x4+3x6+4x8 ------------------------------- 2x3+4x6+6x9+8x12简便方法啊(1x2+2x4+3x6+4x8 )/( 2x3+4x6+6x9+8x12)
(1x2+2x4+3x6+4x8)/(2x3+4x6+6x9+8x12)简便方法啊,
1x2+2x4+3x6+4x8+5x10+.+20x40 怎么算?
1x2+2x4+3x6+4x8+5x10+.+20x40 简便计算
1x2+2x3+3x4+4x5+5x6---+99x100=?
1x2+2x3+3x4+4x5+5x6+.+99x100
巧算:1x2+2x3+3x4+4x5+5x6+6x7...+8x9
x1-x2+x3=1x2-x3+x4=21若x1,x2,x3,x4,x5满足方程组 x3-x4+x5=3x4-x5+x1=4x5-x1+x2=5求x2 x3 x4的值2已知 x1+x4+x6+x7=39 x2+x4+x5+x7=49 x3+x5+x6+x7=41 x4+x7=13 x5+x7=14 x6+x7=9 x1+x2+x3+x4+x5+x6+x7=9求x7的值若x1,x2,x3,x4,x5满足方程组 x1-x
x8+x7+x6 +x5+x4+x3+x2+x+1因式分解
x8+x7+x6+x5+x4+x3+x2+x+1因式分解
x8+x6+x4+x2+1=0 化简
1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+......1/2008x2009
1/1x2+2/1x3+3/1x4+4/1x5+5/1x6+6/1x7=
1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9+9x10+10x11