作业帮若2!=2x3,=3x4x5,=5x6x7x8x9,按此规则计算4!/6!.
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若2!=2x3,=3x4x5,=5x6x7x8x9,按此规则计算4!/6!.
若2!=2x3,=3x4x5,=5x6x7x8x9,按此规则计算4!/6!.
若2!=2x3,=3x4x5,=5x6x7x8x9,按此规则计算4!/6!.
4!/6!
=(4×5×6×7)/(6×7×8×9×10×11)
=20/(8×9×10×11)
=1/396
4X5x6x7/6x7X8X9X10X11=1/396
若2!=2x3,3!=3x4x5,5!=5x6x7x8x9，按此规则计算
4!/6!
=(4×5×6×7)/(6×7×8×9×10×11)
=20/(8×9×10×11)
=1/396
若2!=2x3,=3x4x5,=5x6x7x8x9 ,那么4!/5!
若2!=2x3,=3x4x5,=5x6x7x8x9 ,那么4!/6!
若2!=2x3,3!=3x4x5,5!=5x6x7x8x9,按此规则计算4!/6!.
若2!=2x3,=3x4x5,=5x6x7x8x9,按此规则计算4!/6!.
1x2=1|3(1x2x3-0x1x2) 2x3=1|3(2x3x4-1x2x3) 3x4=1|3(3x4x5-2x3x4)由此推断1x2x3+2x3x4+3x4x5.7x8x9=?
1x2=1/3x(1x2x3-0x1x2)2x3=1/3x(2x3x4-1x2x3)3x4=1/3x(3x4x5-2x3x4)求1x2x3+2x3x4+3x4x5+...+7x8x9=?
1x2x3+2x3x4+3x4x5+...+7x8x9=,
1x2X3+2x3X4+3x4X5+…+7X8X9=?
1x2+2x3+3x4+...+n(n+1)=?1x2x3+2x3x4+3x4x5+...+n(n+1)(n+2)=?
1x2x3+2x3x4+3x4x5+.+7x8x9=?1x2=1/3(1x2x3-0x1x2)2x3=1/3(2x3x4-1x2x3)3x4=1/3(3x4x5-2x3x4)1x2+2x3+3x4=1/3x3x4x5=20
1x2=1/3(1x2x3=0x1x2 ) 2x3=1/3(2x3x4-1x2x3) 3x4=1/3(3x4x5- 2x3x4) 1x2+2x3+3x4+...+nx(n+1)=
1x2+2x3+3x4=3分2x(3x4)+3分3x(3x4)=3分3x4x5规律计算2008x2009分之1x(1x2+2x3+3x4+.+2008x2009)
1x2+2x3+3x4+…+10x11=?1x2=1/3(1x2x3-0x1x2)2x3=1/3(2x3x4-1x2x3)3x4=1/3(3x4x5-2x3x4)1x2+2x3+3x4=1/3x3x4x5=201x2+2x3+3x4+…+n(n+1)=?《2010汕头中考》1x2x3+2x3x4+3x4x5+....+7x8x9=?
解方程配方法6x平方=3-5x6x平方=3-5x
1x2=三分之一｛1x2x3-0x1x2｝；2x3-三分之一｛2x3x4-1x2x3｝：3x4-三分之一｛3x4x5-2x3x4}.由三个等式相加,可得1x2+2x3+3x4=三分之一x3x4x5=20问｛1｝1x2+2x3+3x4+.+10x11｛写出过程｝；｛2｝1x2+2x3+3x4...+n乘{n+1}
2/1x2x3+2/2x3x4+2/3x4x5+2/4x5x6+...+2/98x99x100=
1/1x2x3+1/2x3x4+1/3x4x5+1/4x5x6+1/5x6x7=?这类题
1x2x3+2x3x4+3x4x5+4x5x6+...+n(n+1)(n+2)=