-4/8 nha các bạn

Câu 1:

\(-\frac48\) = \(\frac{x}{10}\) = - \(\frac{7}{y}\) = \(\frac{z}{-24}\)

- \(\frac48\) = \(\frac{x}{10}\) ⇒ \(x\) = - \(\frac48\) x 10 = -5

\(\frac{-4}{8}\) = \(\frac{-7}{y}\) ⇒ y = -7 : ( \(-\frac48\)) = - 7 x (-8/4) = 14

\(-\frac48\) = \(\frac{z}{-24}\) ⇒ z = - \(\frac48\) x (-24) = 12

Vậy (x; y; z)= (-5; 14; 12)

LẠM DỤNG QUÁ NHIỀU

a) x = 1

a.X=\(\frac{25}{7}\)

Bài 1 : Ta có:

\(\frac{7+\frac{7}{11}+\frac{7}{23}+\frac{7}{31}}{9+\frac{9}{11}+\frac{9}{23}+\frac{9}{31}}\)

= \(\frac{7.\left(1+\frac{1}{11}+\frac{1}{23}+\frac{1}{31}\right)}{9.\left(1+\frac{1}{11}+\frac{1}{23}+\frac{1}{31}\right)}\)

= \(\frac{7}{9}\)

Bài 2 :

 \(\frac{x}{2}+\frac{3x}{4}+\frac{5x}{6}=\frac{10}{24}\)

=> \(\frac{12x+18x+20x}{24}=\frac{10}{24}\)

=> 50x = 10

=> x = 10 : 50

=> x = 1/5

Bài 3 : Để A nhận giá trị nguyên thì 3 \(⋮\)x + 3

                                         <=> x + 3 \(\in\)Ư(3) = {1; -1; 3; -3}

Lập bảng :

Vậy 

a) x = 5 . 6 : 24 = 1,25

b) y = 14 . (-4) : 20 = -2,8

a) Ta có: \(\frac{x}{9}=\frac{-12}{27}\)

=> \(27.x=-12.9\)

=> \(27x=-108\)

=> \(x=108:27\)

=>\(x=4\)

NHiều lắm ạ

k mình

\(C\text{ó}-v\text{ }\text{ô}-S\text{ố}-c\text{ác}-s\text{ố}-nguy\text{ê}n-x;y\)

\(b,\frac{z}{7}=-\frac{11}{-28}\)

\(\Leftrightarrow z.\left(-28\right)=-11.7\)

\(\Leftrightarrow z.\left(-28\right)=-77\)

\(\Leftrightarrow z=\frac{11}{4}\)

\(a,-\frac{2}{3}=\frac{x-3}{-6}=\frac{10}{5-y}=\frac{4-2z}{9}\)

Xét :

\(-\frac{2}{3}=\frac{x-3}{-6}\)

\(\Leftrightarrow-2.\left(-6\right)=\left(x-3\right).3\)

\(\Leftrightarrow12=\left(x-3\right).3\)

\(\Leftrightarrow4=x-3\Leftrightarrow x=7\)

Xét 

\(-\frac{2}{3}=\frac{10}{5-y}\)

\(\Leftrightarrow-2.\left(5-y\right)=10.3\)

\(\Leftrightarrow-10+2y=30\)

\(\Leftrightarrow2y=40\Leftrightarrow y=20\)

Xét : 

\(-\frac{2}{3}=\frac{4-2z}{9}\)

\(\Leftrightarrow-2.9=\left(4-2z\right).3\)

\(\Leftrightarrow-18=\left(4-2z\right).3\)

\(\Leftrightarrow-6=4-2z\)

\(\Leftrightarrow10=2z\Leftrightarrow z=5\)

Vậy \(\left(x;y;z\right)=\left(7;20;5\right)\)

NHÂN CHÉO

a)

x.y =3.7

x.y= 21

=> x và y thuộc Ư(21)

Sau đó bn tự thay x,y nha