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9 tháng 2 2018

A + B + C = 149,739

C = A x 10

A = B x 10 => C = B x 100

=> B x 10 + B + B x 100 = 149, 739

   B = 149,739 : 111

   B = 1,349

   A = 1,349 x 10 = 13,49

   C = 13,49 x 10 = 134,9

                                          Đáp số: A = 13,49; B = 1,349; C = 134,9

Khi ta chuyển dấu phẩy của số A sang phải 1 chữ số thì ta được số mới(số thứ 1) gấp 10 lần số A, mà số đó(số thứ 1) là C nên suy ra C gấp 10 lần A(*1*)

Khi ta chuyển dấu phẩy của số A sang trái 1 chữ số thì ta được số mới(số thứ 2), số A sẽ gấp số mới đó(số thứ 2) 10 lần, mà số mới đó(số thứ 2) là B nên suy ra A gấp 10 lần B.(*2*)

Từ (*1*),(*2*) suy ra C sẽ gấp B: \(10\cdot10=100\)lần.

Theo đề bài, ta có: \(A+B+C=139,416\)

Vì C gấp 100 lần B suy ra \(C=100\cdot B\)

Vì A gấp B 10 lần suy ra \(A=10\cdot B\)

Thay \(A=10\cdot B;C=100\cdot C\),ta có:

\(100\cdot B+10\cdot B+B=139,416\)

\(B\cdot\left(100+10+1\right)=139,416\)

\(B\cdot111=139,416\)

\(B=139,416:111\)

\(B=1,256\)

\(\Rightarrow A=1,256\cdot10=12,56;C=1,256\cdot100=125,6\)

Vậy: A=12,56 ; B=1,256 ; C=125,6.

18 tháng 5 2018

Ta có \(\frac{a}{100}=b\)( chia cho 100 tức là dời dấu phẩy của a sang bên trái 2 chữ số)

         \(\frac{b}{1000}=c\)( chia cho 1000 tức là dời dấu phẩy của b sang bên trái 3 chữ số)

=> \(a=100b\)

=> \(a+b+c=100b+b+\frac{b}{1000}=\frac{100000b}{1000}+\frac{1000b}{1000}+\frac{b}{1000}=2793,8976\)

=> \(\frac{100000b+1000b+b}{1000}=2793,8976\)

=> \(\frac{101001b}{1000}=2793,8976\)

=> \(101001b=2793,8973.1000=2793897,3\)

rồi bạn tìm b

sau đó tìm a và c

tự làm nhé....................................

17 tháng 12 2015

số A là 19,98

Tick nha nguyen thuy linh

6 tháng 12 2016

cau 1 :13,57


 

1 tháng 3 2017

1 . 12,34

2 . 13,57

3 . 12,45

4 . 24,54

25 tháng 11 2020

19,89 CHÚC BẠN HỌC TỐT

24 tháng 12 2020

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