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数列求和(六)

\[ \sum\limits_{j = 1}^n {\frac{{2j - 1}}{{j\left( {j + 1} \right)\left( {j + 2} \right)}}} = \frac{3}{4} - \frac{2}{{n + 2}} + \frac{1}{{2\left( {n + 1} \right)\left( {n + 2} \right)}} \]

\[ \sum\limits_{j = 1}^n {\frac{{j + 2}}{{j\left( {j + 1} \right)\left( {j + 3} \right)}}} \] \[ = \frac{{29}}{{36}} - \frac{1}{{n + 3}} - \frac{3}{{2\left( {n + 2} \right)\left( {n + 3} \right)}} - \frac{4}{{3\left( {n + 1} \right)\left( {n + 2} \right)\left( {n + 3} \right)}} \]

\[ \sum\limits_{j = 1}^n {\frac{{j2^{j - 1} }}{{\left( {j + 1} \right)\left( {j + 2} \right)}}} = \frac{{2^n }}{{n + 2}} - \frac{1}{2} \]

\[ \sum\limits_{j = 1}^n {\frac{{j^2 4^j }}{{\left( {j + 1} \right)\left( {j + 2} \right)}}} = \frac{2}{3} + \frac{{\left( {n - 1} \right)4^{n + 1} }}{{3\left( {n + 2} \right)}} \]

\[ \sum\limits_{j = 1}^n {\frac{{j + 2}}{{j\left( {j + 1} \right)2^j }}} = 1 - \frac{1}{{\left( {n + 1} \right)2^n }} \]

\[ \sum\limits_{j = 1}^n {\frac{{2j + 3}}{{j\left( {j + 1} \right)3^j }}} = 1 - \frac{1}{{\left( {n + 1} \right)3^n }} \]

\[ \sum\limits_{j = 1}^n {\frac{{\left( { - 1} \right)^{j - 1} 2^j }}{{\left[ {2^j + \left( { - 1} \right)^j } \right]\left[ {2^{j + 1} + \left( { - 1} \right)^{j + 1} } \right]}}} = \frac{1}{3}\left[ {1 + \frac{{\left( { - 1} \right)^{n + 1} }}{{2^{n + 1} + \left( { - 1} \right)^{n + 1} }}} \right] \]

\[ \sum\limits_{j = 1}^n {\frac{{b\left( {b + 1} \right) \cdots \left( {b + j - 1} \right)}}{{a\left( {a + 1} \right) \cdots \left( {a + j - 1} \right)}}} = \frac{1}{{b - a + 1}}\left[ {\frac{{b\left( {b + 1} \right) \cdots \left( {b + n} \right)}}{{a\left( {a + 1} \right) \cdots \left( {a + n - 1} \right)}} - b} \right] \] 

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参阅
  1. 数学 - 数学符号 - 数学索引
  2. 手册 = 初中数学手册 + 高中数学手册 + 数学手册 + 实用数学手册
  3. 初等数学 = 小学数学 + 中学数学 ( 初中数学 + 高中数学 )
  4. 高等数学 = 基础数学 ( 代数 + 几何 + 分析 ) + 应用数学
  5. 公式 - 定理 - - 函数图 - 曲线图 - 平面图 - 立体图 - 动画 - 画画
  6. 书单 = 数学 + 物理 + 化学 + 计算 + 医学 + 英语 + 教材 - QQ群下载书
  7. 数学手册计算器 = 数学 + 手册 + 计算器 + 计算机代数系统
  8. 检测 - 例题 :

`(d^0.5y)/dx^0.5 = sin(x-1)*sin(y-1) ` == ? `(d^0.5y)/dx^0.5 -cosh(y)-sinh(y)=0 ` == ? `(d^1.6y)/(dx^1.6)-int y(x) (dx)^(0.8)-y-exp(x)=0` == ? `int y(x) (dx)^0.5 -y-exp(x)`=0 == ? `(d^0.5y)/dx^0.5-exp(y)*x=0` == ? `(d^0.5y)/dx^0.5-exp(y)*y=0` == ? `(d^0.5y)/dx^0.5=cos(x)/x*y` == ? `y*(dy^0.5)/dx^0.5-sqrt(x)-1=0` == ? `(d^1.2y)/(dx^1.2)-2(d^0.6y)/dx^0.6+y-exp(x)=0` == ? `(d^0.5y)/dx^0.5=cos(y)*exp(x)*x` == ? `(d^1.6y)/(dx^1.6)-2(d^0.8y)/dx^0.8+y-exp(x)=0` == ? `(d^0.5y)/dx^0.5-exp(y)*sqrt(x)=0` == ? `(d^1.6y)/(dx^1.6)-3 (d^0.8y)/dx^0.8+2y-exp(x)=0` == ? `(d^0.5y)/dx^0.5` +log(y-1)-exp(x)-x=0 == ? `(d^0.5y)/dx^0.5-exp(y)*sin(x)=0` == ? `(d^0.5y)/dx^0.5 = y*sin(x)/x ` == ? `y^((0.5))(x) -4 exp(x)*y-exp(x)=0` == ? `(dy^0.5)/dx^0.5 = 1/(x-y)` == ? `dy/dx-(d^0.5y)/dx^0.5` - y - exp(x)=0 == ? `(dy)/dx -exp(y-1)-x-x^2=0` == ? `(d^1.2y)/(dx^1.2)-3dy^0.6/dx^0.6+2y-exp(x)=0` == ? `dy/dx-(d^0.5y)/dx^0.5-y-1`=0 == ? `(d^0.5y)/dx^0.5-cos(y)*sin(x)=0` == ? `(d^1.6y)/(dx^1.6)-(d^0.8y)/dx^0.8-y-exp(4x)=0` == ? `dy/dx-exp(y-1)-exp(x)=0` == ? `(dy)/dx - 2(d^0.5y)/dx^0.5-y-exp(x)=0` == ? `(d^1.6y)/(dx^1.6)-(d^0.8y)/dx^0.8-y-exp(x)=0` == ? `(d^0.5y)/dx^0.5 -e^(4x)-y`=0 == ? `y^((0.5))(x) - exp(x)*y-exp(x)=0` == ? `y^((0.5))(x) - exp(x)*y-4exp(x)=0` == ? `(dy)/dx -3(d^0.5y)/dx^0.5 +2y-exp(x)=0` == ? `y*(d^0.5y)/dx^0.5-sqrt(x)-1=0` == ? `y^((1))(x)-exp(y-1)-x=0` == ? `(d^1.6y)/(dx^1.6)-(d^0.8y)/dx^0.8-2y-exp(x)=0` == ? `(d^1.6y)/(dx^1.6)-(d^0.8y)/dx^0.8-y-exp(4x)=0` == ? `(d^0.5y)/dx^0.5 - log(y-1) - exp(x) + x=0` == ? `(dy)/dx +asin(y-1) - cos(x)-x=0` == ? `(d^1.6y)/(dx^1.6)-3(d^0.8y)/dx^0.8+2y-exp(x)=0` == ? `(dy)/(dx) -sqrt(y-1)-x-1 =0` == ? ` (dy)/(dx) -exp(y-1)-exp(x) = 0` == ? `(dy)/dx` +asinh(y-1)-cosh(x)-x =0 == ? `((d^(1/2)y)/dx^(1/2))^2 -3y* (dy^0.5)/dx^0.5 + 2y^2 = 0` == ? `(dy^0.5)/dx^0.5 = cos(x)*cos(y-1)` == ? `(d^0.5y)/dx^0.5 +log(y-1)-exp(x)-x=0` == ? `(dy^0.5)/dx^0.5 = sin(x-1)*exp(y-1)` == ? `y*(d^2y)/dx^2-(dy/dx)^2+1=0` == ? `y^((1))(x)-exp(y-1)-log(x)=0` == ? `(d^2y)/dx^2 *exp(x)- exp(y-1)=0` == ? `(d^1.6y)/(dx^1.6)-2 (d^0.8y)/dx^0.8-y-exp(x)=0` == ? `(d^1.6y)/(dx^1.6)-2 (d^0.8y)/dx^0.8+y-exp(x)=0` == ? `(dy)/dx -3 (d^0.5y)/dx^0.5+2y-exp(x)=0` == ? `y^((0.5))(x) - x*y-x=0` == ? `y*(dy^3)/dx^3-x^3-3x^2-3x-1=0` == ? `y^((1.8))(x)-2y^((0.9))(x) +y-1=0` == ? `y^((0.5))(x)=1/(x*y-1)` == ? `y^((2))(x)*y^2-x^2-2x-1=0` == ? `((d^0.5y)/dx^0.5)^2 -5(d^0.5y)/dx^0.5 +6=0` == ? `y^((0.5))(x) -2 exp(x)*y-4exp(x)=0` == ? `(d^1.6y)/(dx^1.6)-(d^0.8y)/dx^0.8-y-exp(x)=0` == ? `y^(0.5)(x)=2y*exp(x)` == ? `y^((0.5))(x)-exp(x)*y^2=0` == ? `(d^1.6y)/(dx^1.6)-2(d^0.8y)/dx^0.8+y-exp(x)=0` == ? `y^((1))(x)-y^2-x*y=0` == ? `y^((1))(x)-y^((0.5))(x) -y-1=0` == ? `y^((2))(x) -y^2-x^2=0` == ? `y^((2))(x) -y^2-x^2-2x*y=0` == ? `y^((0.5))(x) -int y(x) (dx)^0.5-y-exp(x)=0` == ? `d^0.5/dx^0.5 y -2cos(y)*exp(x)=0` == ? `d^0.5/dx^0.5 y -4sin(y)*exp(x)=0` == ? `(d^0.5y)/dx^0.5=sin(x^2)*y` == ? `(d^0.5y)/dx^0.5-sin(x)*sin(y)=0` == ? `(d^0.5y)/dx^0.5-sinh(x)*sinh(y)=0` == ? `y^((1))(x)=exp(x-y)-x` == ? `x*(d^0.5y)/dx^0.5-y-2x=0` == ? `(d^0.5y)/dx^0.5=sinh(x-1)*sinh(y-1)` == ? `y^((0.5))(x)-exp(-x)*y^2=0` == ? `(d^0.5y)/dx^0.5=y/x*sin(x)` == ? `(dy)/dx-sin(x-y)-1=0` == ? `(d^2.5y)/dx^2.5=y*(d^0.5y)/dx^0.5` == ? `(d^0.5y)/dx^0.5=y*(dy)/dx` == ? `(d^(2-i)y)/dx^(2-i)- y+x=0` == ? `(d^2y)/dx^2=y^3*x^2` == ? `y*(d^2y)/dx^2-x^2-3x-1=0` == ? `y*(d^2y)/dx^2-2x^2-3x-1=0` == ? `(y-x-1)*(d^2y)/dx^2-3x-1=0` == ? `y^2*(d^2y)/dx^2-x^2-4x-4=0` == ? `(y-x-1)*(d^2y)/dx^2-x^2-4x-4=0` == ? `y*(d^2y)/dx^2-2x^2-2x-1=0` == ? `y*(d^3y)/dx^3-6x^3-3x^2-3x-1=0` == ? `y^((0))(x)*y^((1))(x)*y^((2))(x)=x^2` == ? `y^((3))(x)*y^((2))(x)=y^((1/2))(x)` == ? `y^((3))(x)=exp(x)*y^((1))(x)*y^((1/2))(x)` == ? `y^((1/2))(x)*y^((3))(x)=exp(x)` == ? `y^((1/2))(x)*y^((2))(x)=exp(x)` == ? `(d^0.5y)/dx^0.5-2x*y-1=0` == ? `y^2*(d^0.5y)/dx^0.5-x^2-4x-4=0` == ? `exp(y-1)*(d^0.5y)/dx^0.5-x=0` == ? `y*(d^2y)/dx^2-(x-2)*(2x-4)=0` == ? `y*(d^3y)/dx^3-6x^3-4x^2-4x-1=0` == ? `exp(y-1)*(d^2y)/dx^2-exp(x)=0` == ? `y^2*(d^2y)/dx^2-x^2-1=0` == ? `1/y^2*(d^2y)/dx^2-x^2-1=0` == ? `(y-x-1)*(d^3y)/dx^3-(x-2)*(2x-4)*(3x-1)=0` == ? `(d^0.5y)/dx^0.5-2x^2*y^2-8x^2=0` == ? `(d^0.5y)/dx^0.5-2x*y^2-8x=0` == ? `(d^0.5y)/dx^0.5-y^2-2y-2=0` == ? `(d^0.5y)/dx^0.5-log(y-1)*exp(x)=0` == ? `y*(d^2y)/dx^2-(dy/dx)^2-1=0` == ? `(d^2y)/dx^2-asin(y-1)-sin(x)-x=0` == ? `dy/dx*(x--y)-x--y-1 = 0` == ?


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