已知1-1/2=1/2,1/2-1/3=1/6,1/3-1/4=1/12,...根据这些等式解答下列各题.(1)求值:1/1*2+1/2*3+1/3*4+1/4*5+1/5*6(2)化简:1/1*2+1/2*3+1/3*4+...+1/n(n+1)(3)若1/1*2+1/2*3+1/3*4+...+1/n(n+1)=19/20,则n=?
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![已知1-1/2=1/2,1/2-1/3=1/6,1/3-1/4=1/12,...根据这些等式解答下列各题.(1)求值:1/1*2+1/2*3+1/3*4+1/4*5+1/5*6(2)化简:1/1*2+1/2*3+1/3*4+...+1/n(n+1)(3)若1/1*2+1/2*3+1/3*4+...+1/n(n+1)=19/20,则n=?](/uploads/image/z/2711876-68-6.jpg?t=%E5%B7%B2%E7%9F%A51-1%2F2%3D1%2F2%2C1%2F2-1%2F3%3D1%2F6%2C1%2F3-1%2F4%3D1%2F12%2C...%E6%A0%B9%E6%8D%AE%E8%BF%99%E4%BA%9B%E7%AD%89%E5%BC%8F%E8%A7%A3%E7%AD%94%E4%B8%8B%E5%88%97%E5%90%84%E9%A2%98.%281%29%E6%B1%82%E5%80%BC%3A1%2F1%2A2%2B1%2F2%2A3%2B1%2F3%2A4%2B1%2F4%2A5%2B1%2F5%2A6%282%29%E5%8C%96%E7%AE%80%3A1%2F1%2A2%2B1%2F2%2A3%2B1%2F3%2A4%2B...%2B1%2Fn%28n%2B1%29%283%29%E8%8B%A51%2F1%2A2%2B1%2F2%2A3%2B1%2F3%2A4%2B...%2B1%2Fn%28n%2B1%29%3D19%2F20%2C%E5%88%99n%3D%3F)
已知1-1/2=1/2,1/2-1/3=1/6,1/3-1/4=1/12,...根据这些等式解答下列各题.(1)求值:1/1*2+1/2*3+1/3*4+1/4*5+1/5*6(2)化简:1/1*2+1/2*3+1/3*4+...+1/n(n+1)(3)若1/1*2+1/2*3+1/3*4+...+1/n(n+1)=19/20,则n=?
已知1-1/2=1/2,1/2-1/3=1/6,1/3-1/4=1/12,...根据这些等式解答下列各题.
(1)求值:1/1*2+1/2*3+1/3*4+1/4*5+1/5*6
(2)化简:1/1*2+1/2*3+1/3*4+...+1/n(n+1)
(3)若1/1*2+1/2*3+1/3*4+...+1/n(n+1)=19/20,则n=?
已知1-1/2=1/2,1/2-1/3=1/6,1/3-1/4=1/12,...根据这些等式解答下列各题.(1)求值:1/1*2+1/2*3+1/3*4+1/4*5+1/5*6(2)化简:1/1*2+1/2*3+1/3*4+...+1/n(n+1)(3)若1/1*2+1/2*3+1/3*4+...+1/n(n+1)=19/20,则n=?
1/1*2+1/2*3+1/3*4+1/4*5+1/5*6
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)
=1-1/6
=5/6
1/1*2+1/2*3+1/3*4+...+1/n(n+1)
=(1-1/2)+(1/2-1/3)+……+[1/n-1/(n+1)
=1-1/(n+1)
=n/(n+1)
1/1*2+1/2*3+1/3*4+...+1/n(n+1)=19/20
所以n/(n+1)=19/(19+1)
所以n=19
1/1*2+1/2*3+...+1/n(n+1)
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+...(1/n-1/n+1)
=1-1/(n+1)
=n/(n+1)
所以
(1)=5/6
(2)=n/(n+1)
(3) n=19
(1) 1/1*2+1/2*3+1/3*4+1/4*5+1/5*6
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)
=1-1/6
=5/6
(2)
1/1*2+1/2*3+1/3*4+...+1/n(n+1)
=(1-1/2)+(1/2...
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(1) 1/1*2+1/2*3+1/3*4+1/4*5+1/5*6
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)
=1-1/6
=5/6
(2)
1/1*2+1/2*3+1/3*4+...+1/n(n+1)
=(1-1/2)+(1/2-1/3)+……+[1/n-1/(n+1)
=1-1/(n+1)
=n/(n+1)
(3)
因为1/1*2+1/2*3+1/3*4+...+1/n(n+1)=19/20
所以n/(n+1)=19/(19+1)
所以n=19
THAT IS ALL RIGHT
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