问两道今天不会做的数学题,拜托各位大侠帮帮忙,把过程写出来,谢谢
1/1×4+1/4×7+1/7×10+···+1/2002×2005的值-3.14×35.2+6.28×(-23.3)-1.57×36.4...
1/1×4+1/4×7+1/7×10+···+1/2002×2005的值
-3.14×35.2+6.28×(-23.3)-1.57×36.4 展开
-3.14×35.2+6.28×(-23.3)-1.57×36.4 展开
展开全部
1/1*4+1/4*7+1/7*10+......+1/2002*2005
=(1/3)[(1/1-1/4)+(1/4-1/7)+(1/7-1/10)+。。。。。+
(1/2001-1/2002)+(1/2002-1/2005)]
=(1/3)[1-1/2005]=668/2005
-3.14×35.2+6.28×(-23.3)-1.57×36.4
=-3.14×35.2+3.14×(-46.6)-3.14×18.2
=3.14×(-35.2-46.6-18.2)
=3.14×(-100)
=-314
=(1/3)[(1/1-1/4)+(1/4-1/7)+(1/7-1/10)+。。。。。+
(1/2001-1/2002)+(1/2002-1/2005)]
=(1/3)[1-1/2005]=668/2005
-3.14×35.2+6.28×(-23.3)-1.57×36.4
=-3.14×35.2+3.14×(-46.6)-3.14×18.2
=3.14×(-35.2-46.6-18.2)
=3.14×(-100)
=-314
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