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25 tháng 2 2021

`A)2/3=x/60`

`=>40/60=x/60`

`=>x=40`

`B)-1/2=y/18`

`=>-9/18=y/18`

`=>y=-9`

`C)3/x=y/35=-36/84`

Mà `-36/84=(-3 xx 12)/(7 xx 12)=-3/7`

`=>3/x=-3/7`

`=>x=-7`

`y/35=-3/7=-15/35`

`=>y=-15`

`D)7/x=y/27=-42/54`

Mà `-42/54=(-7 xx 6)/(9 xx 6)=-7/9`

`=>7/x=-7/9`

`=>x=-9`

`y/27=-7/9=-21/27`

`=>y=-21`

25 tháng 2 2021

Ông viết rõ ràng đc ko?

a: =>y/15=-2/3

hay y=-10

b: 2/x=x/18

nên \(x^2=36\)

hay \(x\in\left\{6;-6\right\}\)

c: x/9=16/x

nên \(x^2=144\)

hay \(x\in\left\{12;-12\right\}\)

14 tháng 2 2022

a)x=-10
b)x=-6

c)x=-12 nhé

13 tháng 2 2020

\(\frac{7}{-9}=\frac{-21}{27}=\frac{-42}{54}\)

19 tháng 2 2021

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31 tháng 7 2023

\(\dfrac{4}{x}=\dfrac{y}{21}=\dfrac{28}{49}=\dfrac{28:7}{49:7}=\dfrac{4}{9}\\ Vậy:x=\dfrac{4.9}{4}=9\\ y=\dfrac{4.21}{9}=\dfrac{28}{3}\)

31 tháng 7 2023

\(\dfrac{x}{2}=\dfrac{3}{y}\\ \Leftrightarrow x.y=2.3=6\\ Vậy:\left[{}\begin{matrix}\left(x;y\right)=\left(1;6\right)=\left(6;1\right)\\\left(x;y\right)=\left(2;3\right)=\left(3;2\right)\end{matrix}\right.\)

a: \(\left(x,y\right)\in\left\{\left(1;-21\right);\left(-21;1\right);\left(-1;21\right);\left(21;-1\right);\left(3;-7\right);\left(-7;3\right);\left(-3;7\right);\left(7;-3\right)\right\}\)

b: \(\Leftrightarrow\left(x,y-3\right)\in\left\{\left(1;-6\right);\left(-6;1\right);\left(2;-3\right);\left(-3;2\right);\left(-2;3\right);\left(3;-2\right);\left(6;-1\right);\left(-1;6\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(1;-3\right);\left(-6;4\right);\left(2;0\right);\left(-3;-1\right);\left(-2;6\right);\left(3;1\right);\left(6;2\right);\left(-1;9\right)\right\}\)

a: x/2=-5/y

=>xy=-10

=>\(\left(x,y\right)\in\left\{\left(1;-10\right);\left(-10;1\right);\left(-1;10\right);\left(10;-1\right);\left(2;-5\right);\left(-5;2\right);\left(-2;5\right);\left(5;-2\right)\right\}\)

b: =>xy=12

mà x>y>0

nên \(\left(x,y\right)\in\left\{\left(12;1\right);\left(6;2\right);\left(4;3\right)\right\}\)

c: =>(x-1)(y+1)=3

=>\(\left(x-1;y+1\right)\in\left\{\left(1;3\right);\left(3;1\right);\left(-1;-3\right);\left(-3;-1\right)\right\}\)

=>\(\left(x,y\right)\in\left\{\left(2;2\right);\left(4;0\right);\left(0;-4\right);\left(-2;-2\right)\right\}\)

d: =>y(x+2)=5

=>\(\left(x+2;y\right)\in\left\{\left(1;5\right);\left(5;1\right);\left(-1;-5\right);\left(-5;-1\right)\right\}\)

=>\(\left(x,y\right)\in\left\{\left(-1;5\right);\left(3;1\right);\left(-3;-5\right);\left(-7;-1\right)\right\}\)

15 tháng 2 2019

7/x=y/27=-42/54=-7/9

7/x=-7/9 nên x=-9

y/27=-7/9=-21/27 nên y=-21

19 tháng 2 2021

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a: =>x/-3=3

hay x=-9

b: =>x/9=-1/9

hay x=-1

c: =>x+1/5=-1/3

hay x=-8/15

d: =>-7/x=-7/9

hay x=9

14 tháng 2 2022

a, \(\dfrac{x}{-3}=3\Leftrightarrow x=-9\)

b, \(\dfrac{x}{9}=-\dfrac{1}{9}\Rightarrow x=-1\)

c, \(\dfrac{x+3}{15}=-\dfrac{6}{15}\Rightarrow x=-9\)

d, \(\dfrac{42}{-54}=-\dfrac{42}{6x}\Rightarrow6x=54\Leftrightarrow x=9\)

10 tháng 2 2021

a) 

\(\left(x+1\right)\left(y-2\right)=5\\ \Rightarrow\left(x+1\right),\left(y-2\right)\inƯ\left(5\right)=\left\{1;-1;5;-5\right\}\)

Ta có bảng:

x+11-15-5
y-25-51-1
x0-24-6
y7-331

Vậy \(\left(x;y\right)=\left(0;7\right),\left(-2;-3\right),\left(4;3\right),\left(-6;1\right)\)

 

 

10 tháng 2 2021

b) 

\(\left(x-5\right)\left(y+4\right)=-7\\ \Rightarrow\left(x-5\right),\left(y+4\right)\inƯ\left(-7\right)=\left\{1;-1;7;-7\right\}\)

Ta có bảng:

x-51-17-7
y+4-77-11
x6412-2
y-113-5-3

Vậy \(\left(x;y\right)=\left(6;-11\right),\left(4;3\right),\left(12;-5\right),\left(-2;-3\right)\)