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3十5十7十9十11……十49的简便计算方法

1十2十3十4十5十6十7......十49十50 =(1十50)*50/2 =51*50/2 =2550/2 =1275 你的认可是我解答的动力,请采纳

1到49共49个连续整数。 1+49=50 2+48=50...24+26=50 另外多一个25 所以,应该是 24x50+25=1225

原式=(1+50)×50÷2 =51×25 =1275 可以用等差数列的求和公式计算 原式=(1+50)×50÷2 =51×25 =1275 等差数列是常见数列的一种,如果一个数列从第二项起,每一项与它的前一项的差等于同一个常数,这个数列就叫做等差数列 星道三好学生回答,不知...

1十2十3十4十5十……十46十47十48十49 (1+49)+(2+48)+....... +(24+26)+25 =24*50+25 =1225 .

用首尾相加法求和: (1+49)*25/2 =25*25=625

1十2十3十4十…十48十49十5O =(1+50)×(50÷2) =51×25 =1275

1十2十3十4十5十十50十49十48十十3十2十1 =(1+49)+(2+48)(3+47)....(49+1)+50 =50*49+50 =50*50 =2500

7×5/49+3/14 =5/7+3/14 =10/14+3/14 =13/14

原式 49.8x2.73+2.73x50.3+0.273 =49.8x2.73+2.73x50.3+2.73x0.1 =2.73x(49.8+50.3+0.1) =2.73x(100.1+0.1) =2.73x100.2 =2.73x100+2.73x0.2 =273+0.546 =273.546

49.8x2.73+2.73x50.3+0.273 =49.8x2.73+2.73x50.3+2.73x0.1 =2.73x(49.8+50.3+0.1) =2.73x(100.1+0.1) =2.73x100.2 =2.73x100+2.73x0.2 =273+0.546 =273.546

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