a)y+30%y=1,3

<=>1,3y=1,3

<=>y=1.

b)y+25%y=1/2

<=>1,25y=1/2

<=>y=0,4

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.

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

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

y=-1,3/(1+30%) tự tính :v

y= 1/2 : (1-25%) tự tính :3

sao 1+30% vay bn

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

  y+3/10y=-1,3

y(1+3/10)=-1,3

y(10/10+3/10)=-1,3

13/10y=-13/10

y=-13/10:13/10

y=-1

Vậy y=-1

b,y-25%y=1/2

y-1/4y=1/2

y(1-1/4)=1/2

y(4/4-1/4)=1/2

3/4y=1/2

y=1/2:3/4

y=3/8

Vậy y=3/8

a/ y + 30%y = -1,3  

   => y + \(\frac{3}{10}\)y = -1,3

   => \(\frac{13}{10}\)y = -1,3

   => y = -1

b/ y - 25%.y = \(\frac{1}{2}\)

   => y - \(\frac{1}{4}\)y = \(\frac{1}{2}\)

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

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

\(y\frac{130}{100}=\left(-\frac{130}{100}\right)\)

\(y=\left(-\frac{130}{100}\right):\frac{130}{100}\)

\(y=-1\)

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

\(y\frac{75}{100}=\frac{50}{100}\)

\(y=\frac{50}{100}:\frac{75}{100}\)

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

\(a)\) \(y+30\%=\dfrac{-1}{3}\)

\(\Rightarrow y+\dfrac{3}{10}=\dfrac{-1}{3}\)

\(\Rightarrow y=\dfrac{-19}{30}\)

Vậy ...

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

\(\Rightarrow1y-\dfrac{1}{4}y=\dfrac{1}{2}\)

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

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

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

Vậy .....

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

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

\(\Rightarrow y=\dfrac{-8}{10}\)

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

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

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

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

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

a)y=1

b)y=2/3

a)

\(y+30\%y=-1,3\\ \Leftrightarrow y+\dfrac{3}{10}y=-\dfrac{13}{10}\\ \Leftrightarrow y\left(1+\dfrac{3}{10}\right)=-\dfrac{13}{10}\\ \Leftrightarrow\dfrac{13}{10}y=-\dfrac{13}{10}\\ \Rightarrow y=-\dfrac{13}{10}:\dfrac{13}{10}\\ \Rightarrow y=-1\)

b)

\(y-25\%y=\dfrac{1}{2}\\ \Leftrightarrow y-\dfrac{1}{4}y=\dfrac{1}{2}\\\Leftrightarrow y\left(1-\dfrac{1}{4}\right)=\dfrac{1}{2} \\ \Leftrightarrow\dfrac{3}{4}y=\dfrac{1}{2}\\ \Rightarrow y=\dfrac{1}{2}:\dfrac{3}{4}\\ \Rightarrow y=\dfrac{1}{2}\cdot\dfrac{4}{3}\\ \Rightarrow y=\dfrac{4}{6}\\ \Rightarrow y=\dfrac{2}{3}\)

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

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

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