作业帮1—2/1X(1+2)—3/(1+2)X(1+2+3)—4/(1+2+3)X(1+2+3+4)—…—10/(1+2+3+
来源：学生作业帮 编辑：拍题作业网作业帮 分类：数学作业 时间：2024/05/13 23:23:27
1—2/1X(1+2)—3/(1+2)X(1+2+3)—4/(1+2+3)X(1+2+3+4)—…—10/(1+2+3+…+9）X（1+2+3+…+10）
1+2+3+……+(n-1)=n(n-1)/2
1+2+3+……+n=n(n+1)/2
n/{[1+2+3+……+(n-1)][1+2+3+……+n]}
=n/[n(n-1)/2*n(n+1)/2]
=4/[(n-1)n(n+1)]
=2[1/(n-1)-2/n+1/(n+1)]
1—2/1X(1+2)—3/(1+2)X(1+2+3)—4/(1+2+3)X(1+2+3+4)—…—10/(1+2+3+…+9）X（1+2+3+…+10）
=1-2(1/1-2/2+1/3)-2(1/2-2/3+1/4)-2(1/3-2/4+1/5)-……-2(1/9-2/10+1/11)
=1-2[1/1-2/2+1/2+1/11-2/11+1/12]
=1-2[1/2-1/11+1/12]
=1-2[65/132]
=1-65/66
=1/66
1+2+3+……+n=n(n+1)/2
n/{[1+2+3+……+(n-1)][1+2+3+……+n]}
=n/[n(n-1)/2*n(n+1)/2]
=4/[(n-1)n(n+1)]
=2[1/(n-1)-2/n+1/(n+1)]
1—2/1X(1+2)—3/(1+2)X(1+2+3)—4/(1+2+3)X(1+2+3+4)—…—10/(1+2+3+…+9）X（1+2+3+…+10）
=1-2(1/1-2/2+1/3)-2(1/2-2/3+1/4)-2(1/3-2/4+1/5)-……-2(1/9-2/10+1/11)
=1-2[1/1-2/2+1/2+1/11-2/11+1/12]
=1-2[1/2-1/11+1/12]
=1-2[65/132]
=1-65/66
=1/66
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x+2/x+1-x+3/x+2-x+4/x+3+x+5/x+4
x^5+x^4 = (x^3-x)(x^2+x+1)+x^2+x
x-1)(X-2)(x-3)...(x-50)+x(x-2)(X-3)...(X-50)+...+x(x-1)(x-2)
x(2-1/x)+x/(x^2-2x)÷(3-x)/(x^2-4)
|x^2-3x-4|>x+1
x^4+x^3+x^2+x+1=0,x^2006+x^2005+x^2004+x^2003+x^2002
(x+1-1/1-x)÷(x-x²/x-1) (x-4/x-x-6+ x+2/x-3)÷x+1/x-3
y=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)(x-10)的导数在x=1
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1x+2x+3x+4x+5x+6x+7x…+99x=100
1+x+x^2+x^3+.+x^99+x^100