1/2x1/3+1/3x1/4+.1/8x1/9=
来源:学生作业帮 编辑:神马作文网作业帮 分类:数学作业 时间:2024/09/25 03:25:21
1/2x1/3+1/3x1/4+.1/8x1/9=
1/2x1/3+1/3x1/4+.1/8x1/9
=1/2-1/3+1/3-1/4+……+1/8-1/9
=1/2-1/9
=7/18
再问: 1/12+1/20+1/30+......+1/72
再答: 1/12+1/20+1/30+......+1/72 =1/3X1/4+1/4X1/5+1/5X1/6……+1/8X1/9 =1/3-1/4+1/4-1/5+1/5-1/6……+1/8-1/9 =1/3-1/9 =6/27
再问: 为什么一开始不用1减
再答: 像第一道题用1减的话就变成1/2x1/3+1/3x1/4+......1/8x1/9 =1-1/2+1/2-1/3+1/3-1/4+……+1/8-1/9-1/2 就会多出1/2,那在后面就要减去1/2 1/2X1/3=1/6 而1/2-1/3=1/6
=1/2-1/3+1/3-1/4+……+1/8-1/9
=1/2-1/9
=7/18
再问: 1/12+1/20+1/30+......+1/72
再答: 1/12+1/20+1/30+......+1/72 =1/3X1/4+1/4X1/5+1/5X1/6……+1/8X1/9 =1/3-1/4+1/4-1/5+1/5-1/6……+1/8-1/9 =1/3-1/9 =6/27
再问: 为什么一开始不用1减
再答: 像第一道题用1减的话就变成1/2x1/3+1/3x1/4+......1/8x1/9 =1-1/2+1/2-1/3+1/3-1/4+……+1/8-1/9-1/2 就会多出1/2,那在后面就要减去1/2 1/2X1/3=1/6 而1/2-1/3=1/6
1x1\3+2x1\4+3x1\5+.+2006x1\2008的简便算法
提问:1x1/2+1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7 用简便方法
float x1,x2; x1=3/2; x2=x1/2; printf("%d%.1f",(int)x1,x2); 输
数学计算题:1/2X1/3+1/3X1/4+~~~~~~~+1/8x1/9=? 六年级数学计算题,用六年级数学方法解答
求非齐次线性方程组:2x1-x2+4x3-3x4=-4;x1+x3-x4=-3;3x1+x2+x3=1;7x1+7x3-
已知方程3x²-4x=-1的两根是x1 x2,不解方程,求:1.x2/x1 + x1/x2 2.(x1 - 2
min=(4*x1^2+2*x2^2+4*x1*x2+2*x2+1)*exp(x1);
已知X1*X2=1 ,X1+X2=3 ,求X1三次方+X2三次方
已知x1,x2是方程x·x+3x+1=0的两个实数根·则x1·x1·x1+8x2+20=?
线性方程组 线性方程组1x1+x2 -2x4=-64x1-x2-x3-x4=13x1-x2-x3 =3方程组2X1+MX
用图解法求线性规划?max z = x1+3x2 5x1+10x≤50 X1+X2≥1 X2≤4 X1,X2≥0
求解线性方程组:2X1+3X3=1 x1-X2+2x3=1 X1-3X2+4X3=2