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28 tháng 9 2016

tổng 2 phân số là :

\(\frac{7}{8}\) X 2 = \(\frac{7}{4}\)

Tổng của phân số thứ nhất và 3 lần phân số thứ hai là :

\(\frac{17}{8}\)X 2 = \(\frac{17}{4}\)

phân số thứ hai là:

(\(\frac{17}{4}-\frac{7}{4}\)) X 2 = \(\frac{5}{4}\)

Phân số thứ nhất là :

\(\frac{7}{4}-\frac{5}{4}=\frac{2}{4}\)

Đáp số : \(\frac{5}{4}\)và \(\frac{2}{4}\)

28 tháng 9 2016

Tổng 2 phân số

7/8x2=7/4

Nếu gấp phân số thứ nhất lên 3 lần thì được phân số mới

Tổng của phân số mới với phân số thứ 2 là

17/8x2=17/4

Tổng mới hơn tổng cũ là

17/4-7/4=10/4

Trong 1 tổng nếu 1 số hạng gấp lên n lần thì tổng mới tăng thêm n-1 lần số hạng được tăng => Tổng mới đã tăng so với tổng cũ 3-1=2 lần phân số thứ nhất

Phân số thứ nhất là

10/4:2=5/4

Phân số thứ 2 là

7/4-5/4=1/2

9 tháng 10 2016

thằng chó nguye ngoc anh minh  kia

12 tháng 10 2016

nay ban pham hoang anh sao ban lai noi ban anh minh nhu vay the la khong hay dau

13 tháng 10 2016

bằng 5/4

19 tháng 10 2016

1/2 mình thi rồi

23 tháng 10 2016

1/2 đúng rồi nhưng sao Phạm Hoàng Anh lại chửi bạn?????

25 tháng 10 2016

SAO LẠI CHỬI THẾ ?

21 tháng 11 2016

1/2 moi dung to thi roi. chuc ban hoc tot

23 tháng 11 2016

đáp án của tớ là 1/2

tớ nghĩ bài của Vũ Thùy Ngọc Linh sai bét 

30 tháng 11 2016

không được chửi thế chứ.

3 tháng 12 2016

5/4 la đung

17 tháng 12 2016

Hoang anh sao lai chui ban

18 tháng 12 2016

Câu trả lời của mình là 3/4 mình vừa làm đúng luôn

25 tháng 12 2016

mình cũng ra là 1/2

2 tháng 1 2017

trong violympic mink làm 1/2 đúng đấy !

18 tháng 1 2017

1/2 là đúng đó

4 tháng 2 2017

sai hết không có đáp án nào

1/2 là đúng

13 tháng 2 2017

1/2 đấy mình thử rồi!

mình k cho Usagi.

24 tháng 2 2017

trần thị ái ngu quá 1/2 là đúng đấy con si

11 tháng 3 2017

1/2 hay 5/4

16 tháng 5 2017

sai hat roi

28 tháng 6 2017

dung ko day

28 tháng 6 2017

MẤY EM CHO ANH XIN SĐT

22 tháng 7 2017

cong chua1/2 la dung day

25 tháng 7 2017

\(\frac{5}{4}\)nha bn

...................

k nha

9 tháng 8 2017

1/2 nha

29 tháng 9 2017

1/2 đúng rồi còn gì

22 tháng 10 2017

1/2

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27 tháng 10 2016

Tổng 2 phân số : 7/8 x 2 = 7/4

Tổng 2 phân số sau khi tăng phân số thứ nhất lên 3 lần : 17/8 x 2 = 17/4

Phân số thứ nhất là : (17/4 - 7/4) : 3 = 5/6

Phân số thứ hai là : 7/4 - 5/6 = 11/12 

26 tháng 7 2016

Tổng 2 phân số đó là

7/8 x 2 = 7/4

Tổng của phân số thứ nhất và 3 lần phân số thứ 2 là

17/8 x 2 = 17/4

Phân số thứ 2 là 

(17/4 - 7/4) : 2 = 5/4

Phân số thứ nhất là

7/4 - 5/4 = 2/4

Đ/số : ...

23 tháng 7 2016

Tổng 2 phân số đó là

7/8 x 2 = 7/4

Tổng của phân số thứ nhất và 3 lần phân số thứ 2 là

17/8 x 2 = 17/4

Phân số thứ 2 là 

(17/4 - 7/4) : 2 = 5/4

Phân số thứ nhất là

7/4 - 5/4 = 2/4

Đ/số : ...

Ủng hộ mk nha !!! ^_^

30 tháng 7 2019

Tổng của 2 phân số đó là : 

\(\frac{7}{8}\times2=\frac{7}{4}\)

Tổng mới của chúng là : 

\(\frac{17}{8}\times2=\frac{17}{4}\)

Gọi phân số thứ nhất là a ;phân số thứ hai là b

Theo bài ra ta có : \(a+b=\frac{7}{4}\left(1\right)\)

\(a+3\times b=\frac{17}{4}\left(2\right)\)

Nhân 2 vế của (1) với 3 ta có :

\(3\times\left(a+b\right)=3\times\frac{7}{4}\)

\(\Rightarrow3\times a+3\times b=\frac{21}{4}\left(3\right)\)

Lấy (3) trừ (2) theo vế ta có : 

\(\left(3\times a+3\times b\right)-\left(a+3\times b\right)=\frac{21}{4}-\frac{17}{4}\) 

\(\Rightarrow\left(3\times a-a\right)+\left(3\times b-3\times b\right)=1\)

\(\Rightarrow2\times a=1\)

\(\Rightarrow a=1:2\)

\(\Rightarrow a=\frac{1}{2}\)

Thay a vào 1 ta có : 

\(\frac{1}{2}+b=\frac{7}{4}\)

\(\Rightarrow b=\frac{7}{4}-\frac{1}{2}\)

\(\Rightarrow b=\frac{5}{4}\)

Vậy phân số thứ nhất là \(\frac{1}{2}\); phân số thứ hai là \(\frac{5}{4}\)

DD
28 tháng 9 2021

Tổng của hai phân số ban đầu là: 

\(\frac{7}{8}\times2=\frac{7}{4}\)

Sau khi nhân phân số thứ nhất lên gấp \(3\)lần thì tổng của hai số là: 

\(\frac{17}{8}\times2=\frac{17}{4}\)

Phân số thứ nhất là: 

\(\left(\frac{17}{4}-\frac{7}{4}\right)\div\left(3-1\right)=\frac{5}{4}\)

Phân số thứ hai là: 

\(\frac{7}{4}-\frac{5}{4}=\frac{1}{2}\)

4 tháng 4 2018

Tổng của ba phân số lúc đầu là:            7/6*3=7/2

Tổng của ba phân số sau khi tăng phân số thứ nhất lên 2 lần là:           

                                  41/30*3=41/10

Phân số thứ nhất là:                            [41/10-7/2]:1=3/5

Tổng của ba phân số sau khi tăng phân số thứ hai lên 2 lần là:

                                        13/9*3=13/3

Phân số thứ hai là:                              [13/3-7/2]:1=5/6

Phân số thứ ba là:                               7/2-3/5-5/6=31/15

Mk chắc 100% lun.Bạn nhớ tk mk nha.Chúc bạn học giỏi.

4 tháng 4 2018

Giải Tổng của ba phân số đã cho là:

 7/6 x 3 = 7/2 

Phân số thứ nhất là:

 41/30 x 3 - 7/2 = 3/5 

Phân số thứ hai:

 13/9 x 3 - 7/2 = 5/6 

Phân số thứ ba: 

7/2 - ( 3/5 + 5/6 ) = 31/15

 Đáp số: 3/5 ; 5/6 ; 31/15

31 tháng 3 2019

khó phết

14 tháng 12 2020

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