解方程:1/[x(x+1)]+1/(x+1)(x+2)+1/(x+2)(x+3)+.+1/(x+9)(x+10)=5/12

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解方程:1/[x(x+1)]+1/(x+1)(x+2)+1/(x+2)(x+3)+.+1/(x+9)(x+10)=5/12
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解方程:1/[x(x+1)]+1/(x+1)(x+2)+1/(x+2)(x+3)+.+1/(x+9)(x+10)=5/12
解方程:1/[x(x+1)]+1/(x+1)(x+2)+1/(x+2)(x+3)+.+1/(x+9)(x+10)=5/12

解方程:1/[x(x+1)]+1/(x+1)(x+2)+1/(x+2)(x+3)+.+1/(x+9)(x+10)=5/12
1/[x(x+1)]+1/(x+1)(x+2)+1/(x+2)(x+3)+.+1/(x+9)(x+10)=5/12
1/x-1/(x+1)+1/(x+1)-1/(x+2)+...+1/(x+9)-1/(x+10)=5/12;
1/x-1/(x+10)=5/12;
12(x+10)-12x=5x(x+10);
120=5x²+50x;
x²+10x-24=0;
(x+12)(x-2)=0;
x=2或x=-12;
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裂项啊 1/x-1/(x+10)=5/12 x=2

原式
=1/x-1/(x+1)+1/(x+1)-1/(x+2)+...+1/(x+1998)-1/(x+1999)
=1/x-1/(x+1999)
=1999/[x(x+1999)]

1/[x(x+1)]+1/(x+1)(x+2)+1/(x+2)(x+3)+....+1/(x+9)(x+10)
=1/x-1/(x+1)+1/(x+1)-1/(x+...

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原式
=1/x-1/(x+1)+1/(x+1)-1/(x+2)+...+1/(x+1998)-1/(x+1999)
=1/x-1/(x+1999)
=1999/[x(x+1999)]

1/[x(x+1)]+1/(x+1)(x+2)+1/(x+2)(x+3)+....+1/(x+9)(x+10)
=1/x-1/(x+1)+1/(x+1)-1/(x+2)+...+1/(x+9)-1/(x+10)
=1/x-1/(x+10)
=10/[x(x+10)] = 5/12
5 x(x+10) =120
x(x+10) =24
x² +10x-24 = 0
(x+12)(x-2) = 0
x=-12 或者 2

收起

1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+……+1/(x+9)(x+10)=5/12
1/x-1/(x+1)+1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+……+1/(x+9)-1/(x+10)=5/12
1/x-1/(x+10)=5/12
10/x(x+10)=5/12
5x²+50x=120
x&#...

全部展开

1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+……+1/(x+9)(x+10)=5/12
1/x-1/(x+1)+1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+……+1/(x+9)-1/(x+10)=5/12
1/x-1/(x+10)=5/12
10/x(x+10)=5/12
5x²+50x=120
x²+10x-24=0
(x-2)(x+12)=0
x1=2 x2=-12

收起