几道关于有理数的初中计算题注:“/”就是分数线(1) (-(-1/42)÷(1/6-2/7+2/3-3/14))(2) (1/13-1/2-1/3)÷(-1/78)(3) 1/5×9+1/9×13+……+1/101×105(4)(1/2004-1)×(1/2003-1)×……×(1/10

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几道关于有理数的初中计算题注:“/”就是分数线(1)(-(-1/42)÷(1/6-2/7+2/3-3/14))(2)(1/13-1/2-1/3)÷(-1/78)(3)1/5×9+1/9×13+……+1

几道关于有理数的初中计算题注:“/”就是分数线(1) (-(-1/42)÷(1/6-2/7+2/3-3/14))(2) (1/13-1/2-1/3)÷(-1/78)(3) 1/5×9+1/9×13+……+1/101×105(4)(1/2004-1)×(1/2003-1)×……×(1/10
几道关于有理数的初中计算题
注:“/”就是分数线
(1) (-(-1/42)÷(1/6-2/7+2/3-3/14))
(2) (1/13-1/2-1/3)÷(-1/78)
(3) 1/5×9+1/9×13+……+1/101×105
(4)(1/2004-1)×(1/2003-1)×……×(1/1000-1)

几道关于有理数的初中计算题注:“/”就是分数线(1) (-(-1/42)÷(1/6-2/7+2/3-3/14))(2) (1/13-1/2-1/3)÷(-1/78)(3) 1/5×9+1/9×13+……+1/101×105(4)(1/2004-1)×(1/2003-1)×……×(1/10
(1)
(-(-1/42)÷(1/6-2/7+2/3-3/14))=(-(-1/42)÷(-5/42+19/42))=(-(-1/42)÷(1/3))=1/14
(2)
(1/13-1/2-1/3)÷(-1/78)=(-59/78)÷(-1/78)=59
(3)
1/5×9+1/9×13+1/13×17+……+1/101×105
=1/4 *(4/5×9+4/9×13+4/13×17+……+4/101×105)
=1/4*(1/5 -1/9 +1/9 -1/13 +1/13……-1/101 +1/101 -1/105)
=1/4*(1/5 -1/105)
=1/4*(20/105)
=1/21
(4)
1/2004-1)×(1/2003-1)×……×(1/1000-1)
=(-1)^1005*(2003/2004)*(2002/2003)*(2001/2002)……(1000/1001)*(999/1000)
=-999/2004