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26 tháng 3 2017

a. \(y+30\%y=-1,3\)

\(=>y.\left(1+30\%\right)=-1,3\)

\(=>y.\left(1+\dfrac{3}{10}\right)=-1,3\)

\(=>y.\dfrac{13}{10}=\dfrac{-13}{10}\)

\(=>y=-1\)

b.\(y-25\%y=\dfrac{1}{2}\)

\(=>y.\left(1-25\%\right)=\dfrac{1}{2}\)

\(=>y.\left(1-\dfrac{1}{4}\right)=\dfrac{1}{2}\)

\(=>y.\dfrac{3}{4}=\dfrac{1}{2}\)

\(=>y=\dfrac{1}{2}.\dfrac{4}{3}\)

\(=>y=\dfrac{2}{3}\)

c.\(3\dfrac{1}{3}y+16\dfrac{3}{4}=-13,25\)

\(=>\dfrac{10}{3}y+\dfrac{67}{4}=\dfrac{-53}{4}\)

\(=>\dfrac{10}{3}y=\dfrac{-53-67}{4}\)

\(=>\dfrac{10}{3}y=\dfrac{-120}{4}\)

\(=>\dfrac{10}{3}y=-30\)

\(=>y=-30.\dfrac{3}{10}\)

\(=>y=-9\)

tick cho mk nha

k hiểu chỗ nào thì hỏi mk

26 tháng 3 2017

tại sao lại tu y+30%.y ra la y .(1+30%) gianroi

27 tháng 5 2017

a) \(y+30\%y=-1.3\)

\(y+\dfrac{3}{10}y=\dfrac{-13}{10}\)

\(y\left(1+\dfrac{3}{10}\right)=\dfrac{-13}{10}\)

\(y\left(\dfrac{10}{10}+\dfrac{3}{10}\right)=\dfrac{-13}{10}\)

\(y\cdot\dfrac{13}{10}=\dfrac{-13}{10}\)

\(y=\dfrac{-13}{10}:\dfrac{13}{10}\)

\(y=\dfrac{-13}{10}\cdot\dfrac{10}{13}\)

\(y=-1\)

Vậy \(y=-1\).

b) \(y-25\%y=\dfrac{1}{2}\)

\(y-\dfrac{1}{4}y=\dfrac{1}{2}\)

\(y\left(1-\dfrac{1}{4}\right)=\dfrac{1}{2}\)

\(y\left(\dfrac{4}{4}-\dfrac{1}{4}\right)=\dfrac{1}{2}\)

\(y\cdot\dfrac{3}{4}=\dfrac{1}{2}\)

\(y=\dfrac{1}{2}:\dfrac{3}{4}\)

\(y=\dfrac{1}{2}\cdot\dfrac{4}{3}\)

\(y=\dfrac{2}{3}\)

Vậy \(y=\dfrac{2}{3}\).

c) \(3\dfrac{1}{3}y+16\dfrac{3}{4}=-13.25\)

\(\dfrac{10}{3}y+\dfrac{67}{4}=\dfrac{-53}{4}\)

\(\dfrac{10}{3}y=\dfrac{-53}{4}-\dfrac{67}{4}\)

\(\dfrac{10}{3}y=-30\)

\(y=-30:\dfrac{10}{3}\)

\(y=-30\cdot\dfrac{3}{10}\)

\(y=-9\)

Vậy \(y=-9\).

29 tháng 3 2018

a) y+30%y=−1.3y+30%y=−1.3

y+310y=−1310y+310y=−1310

y(1+310)=−1310y(1+310)=−1310

y(1010+310)=−1310y(1010+310)=−1310

y⋅1310=−1310y⋅1310=−1310

y=−1310:1310y=−1310:1310

y=−1310⋅1013y=−1310⋅1013

y=−1y=−1

Vậy y=−1y=−1.

b) y−25%y=12y−25%y=12

y−14y=12y−14y=12

y(1−14)=12y(1−14)=12

y(44−14)=12y(44−14)=12

y⋅34=12y⋅34=12

y=12:34y=12:34

y=12⋅43y=12⋅43

y=23y=23

Vậy y=23y=23.

c) 313y+1634=−13.25313y+1634=−13.25

103y+674=−534103y+674=−534

103y=−534−674103y=−534−674

103y=−30103y=−30

y=−30:103y=−30:103

y=−30⋅310y=−30⋅310

y=−9y=−9

Vậy y=−9y=−9.

AH
Akai Haruma
Giáo viên
24 tháng 10

Lời giải:

a. $y+30\text{%}y=-1,3$

$y+0,3y=-1,3$

$y(1+0,3)=-1,3$

$y.1,3=-1,3$

$y=(-1,3):1,3=-1$

b.

$y-25\text{%}y=\frac{1}{2}$

$y-0,25y=0,5$

$y(1-0,25)=0,5$

$y.0,75=0,5$

$y=0,5:0,75=\frac{2}{3}$

c.

\(3+\frac{1}{3}y+16+\frac{3}{4}=-13,25\)

$\frac{1}{3}y+19,75=-13,25$
$\frac{1}{3}y=-13,25-19,75=-33$
$y=-33:\frac{1}{3}=-99$

 

4 tháng 4 2018

a, y + 30%y = -1,3

 1.y + 30/100y = -13/10

 1.y + 3/10y  = -13/10

(1 + 3/10). y = -13/10

13/10 .y = -13/10

           y = -13/10 : 13/10

           y = -13/10 . 10/13

           y = -1

b, y - 25%y = 1/2

   1.y - 25/100.y = 1/2

   1.y - 1/4.y = 1/2

   (1 - 1/4) y = 1/2

    3/4 .y = 1/2

           y = 1/2 : 3/4

           y = 1/2 . 4/3

           y = 2/3

câu c mik chưa nghĩ ra

15 tháng 8 2016

a)\(y+30\%y=-1,3\Rightarrow y+\frac{3}{10}y=-1,3\Rightarrow y\left(1+\frac{3}{10}\right)=-1,3\Rightarrow y\times1,3\)\(=-1,3\Rightarrow y=-1\)

b)\(y-25\%y=\frac{1}{2}\Rightarrow y-\frac{1}{4}y=\frac{1}{2}\Rightarrow y\left(1-\frac{1}{4}\right)=\frac{1}{2}\Rightarrow y\times\frac{3}{4}=\frac{1}{2}\Rightarrow y=\frac{1}{2}:\frac{3}{4}\Rightarrow y=\frac{2}{3}\)

c)\(3\frac{1}{3}y+16\frac{3}{4}=13,25\Rightarrow\frac{10}{3}y+\frac{67}{4}=\frac{53}{4}\Rightarrow\frac{10}{3}y=\frac{53}{4}-\frac{67}{4}\Rightarrow\frac{10}{3}y=\frac{-7}{2}\Rightarrow y=\frac{-21}{20}\)

13 tháng 1 2017

-21/20

28 tháng 3 2016

a) ta có :     y + 30/100y = -1,3

           hay       y(1+ 3/10)    = - 13/10

                       y.13/10 = -13/10

                       y= -13/10:13/10

                       y= -1

b)       y - 25/100y=1/2

hay    y(1-1/4)=1/2

         y.3/4 = 1/2

         y=2/3

c)    10/3y + 16,75 = -13,25

       10/3y= -13,25 - 16,75

       10/3y= -30

             y= - 30:10/3

             y= -9

\(y+30\%y=-1,3\\ 130\%y=-1,3\\ \Rightarrow y=\dfrac{-1,3}{130\%}=-1\)

\(x:\dfrac{4}{28}=\dfrac{13}{-19}+\dfrac{8}{25}\\ 7x=-\dfrac{173}{475}\\ x=-\dfrac{\dfrac{173}{475}}{7}=-\dfrac{173}{3325}\)

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