(1+1/2+1/3+...+1/1994)*(1/2+1/3+...+1/1995)-(1-1/2+1/3+..+1/
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(1+1/2+1/3+...+1/1994)*(1/2+1/3+...+1/1995)-(1-1/2+1/3+..+1/1995)*(1/2+1/3+...+1/1994)怎样算?
令 1/2+1/3+...+1/1994 = a
则
(1+1/2+1/3+...+1/1994)*(1/2+1/3+...+1/1995)-(1+1/2+1/3+..+1/1995)*(1/2+1/3+...+1/1994)
= (1+a)*(a+1/1995) - (1+a+1/1995)*a
= (a + a² + 1/1995 + a/1995) - (a + a² + a/1995)
= 1/1995
则
(1+1/2+1/3+...+1/1994)*(1/2+1/3+...+1/1995)-(1+1/2+1/3+..+1/1995)*(1/2+1/3+...+1/1994)
= (1+a)*(a+1/1995) - (1+a+1/1995)*a
= (a + a² + 1/1995 + a/1995) - (a + a² + a/1995)
= 1/1995
2*(1-1/1995*1995)*(1-1/1994*1994)*(1-1993*1993)*.*(1-1/4*4)
把正有理数排序:1/1,2/1,1/2,3/1,2/2,1/3,4/1,3/2,2/3,1/4则数1995/1994
(1) 1,2,3( )
1/1*2+1/2*3+1/3*4+…+1/1993*1994 1/3+1/15+1/35+1/63+...+1/17*
由下列不等式:1>1/2,1+1/2+1/3>1,1+1/2+1/3+.+1/7>3/2,1+1/2+1/3+.+1/1
把正有理数排序:1/1,2/1,1/2,3/1,2/2,1/3,4/1,3/2,2/3,1/4.,问:1995/1949
1994+1/2-(1+1/3)+(2+1/2)-(3+1/3)+(4+1/2)-(5+1/3)+.+(1992+1/2
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