Kết quả ko thì nhanh thôi !

\(\left(a\right)\frac{x}{5}-\frac{5}{2}=31\)

\(x=167\frac{1}{2}\)

\(\left(b\right)\frac{x}{5}-\frac{5}{2}=-31\)

\(x=-142\frac{1}{2}\)

k nhé !

a)\(2x=3y,4y=5z\Leftrightarrow\frac{x}{3}=\frac{y}{2},\frac{y}{5}=\frac{z}{4}\Leftrightarrow\frac{x}{15}=\frac{y}{10},\frac{y}{10}=\frac{z}{8}\)

\(\Rightarrow\frac{x}{15}=\frac{y}{10}=\frac{z}{8}\Leftrightarrow\frac{2x}{30}=\frac{y}{10}=\frac{2z}{16}\)

ADTCDTS=NHAU TA CÓ

\(\frac{2x}{30}=\frac{y}{10}=\frac{2z}{16}=\frac{2x+y-2z}{30+10-16}=\frac{24}{24}=1\)

x=15

y=10

z=8

b) Ta có BCNN(2,3,4)=12

\(\Rightarrow\frac{2x}{12}=\frac{3x}{12}=\frac{4z}{12}\Leftrightarrow\frac{x}{6}=\frac{y}{4}=\frac{z}{3}\)

\(\Rightarrow\frac{x}{6}=\frac{y}{4}=\frac{z}{3}\Leftrightarrow\frac{x^2}{36}=\frac{y^2}{16}=\frac{z^2}{9}\)

ADTCDTS=NHAU TA CÓ

\(\frac{x^2}{36}=\frac{y^2}{16}=\frac{z^2}{9}=\frac{x^2+y^2+z^2}{36+16+9}=\frac{61}{61}=1\)

\(\frac{x^2}{36}=1\Rightarrow x^2=36\Rightarrow x=+_-6\)

\(\frac{y^2}{16}=1\Rightarrow x=+_-4\)

\(\frac{z^2}{9}=1\Rightarrow z=+_-3\)

TUỰ KẾT LUẬN NHA BẠN

C)\(\frac{x-6}{3}=\frac{y-8}{4}=\frac{z-10}{5}\Leftrightarrow\frac{x^2-36}{9}=\frac{y^2-64}{16}=\frac{z^2-100}{25}\)

ADTCDTS=NHAU TA CÓ

\(\frac{x^2-36}{9}=\frac{y^2-64}{16}=\frac{z^2-100}{25}=\frac{\left(x^2-36\right)+\left(y^2-64\right)+\left(z^2-100\right)}{9+16+25}\)

\(=\frac{x^2-36+y^2-64+z^2-100}{50}=\frac{\left(x^2+y^2+z^2\right)-\left(36-64-100\right)}{50}\)

\(=\frac{\left(x^2+y^2+z^2\right)-\left(36+64+100\right)}{50}=\frac{200-200}{50}=\frac{0}{50}=0\)

\(\Rightarrow\frac{x^2-36}{9}=0\Rightarrow x^2-36=0\Rightarrow x^2=36\Rightarrow x=+_-6\)

\(\frac{y^2-64}{16}=0\Rightarrow y^2-64=0\Rightarrow y^2=64\Rightarrow y==+_-8\)

\(\frac{z^2-100}{25}=0\Rightarrow z^2-100=0\Rightarrow z^2=100\Rightarrow z=+_-10\)

TỰ KẾT LUẠN NHA

1 :\(\frac{7}{20}\)

2 \(\frac{1}{4}\)

3 \(\frac{23}{2}\)

4 2187

5 64

6 x=16

7 x=\(\frac{-1}{243}\)

8 mϵ∅

cho mình hỏi cài này là j vậy

Đề 2

1) \(\frac{7}{20}.\)

2) \(\frac{1}{4}.\)

3) \(\frac{23}{2}.\)

4) \(2187.\)

5) \(64.\)

6) \(x=16.\)

7) \(x=\left(-\frac{1}{3}\right)^5\)

8) \(m\in\varnothing.\)

Chúc bạn học tốt!

1, \(\frac{3}{5}+\left(-\frac{1}{4}\right)=\frac{12}{20}+\left(-\frac{5}{20}\right)=\frac{7}{20}\)

2,\(\left(-\frac{5}{18}\right)\left(-\frac{9}{10}\right)=\frac{-5.\left(-9\right)}{18.10}=\frac{45}{180}=\frac{1}{4}\)

3,\(4\frac{3}{5}:\frac{2}{5}=\frac{23}{5}.\frac{5}{2}=\frac{23}{2}\)

\(\begin{array}{l}x - \frac{2}{5} = \frac{1}{2}\\x - \frac{2}{5} + \frac{2}{5} = \frac{1}{2} + \frac{2}{5}\\x = \frac{1}{2} + \frac{2}{5}\\x = \frac{5}{{10}} + \frac{4}{{10}}\\x = \frac{9}{{10}}\end{array}\)

Vậy \(x = \frac{9}{{10}}\).

tick nha dung noi xao do

Theo bải ra ta có : 

| x | + | y | = 2 ( x ; y là số nguyên )
\(\Rightarrow\)-x + (-y) = -2 hoặc  x + y = 2

Khi -x + (-y) = 2 thì ta có : -x + (-y) = 2 hoặc -x + y = -2 hoặc x + (-y) = 2

Nếu -x + (-y) = 2 thì ta có :

-x + (-y) = -1 + (-1) = -2 

Nếu -x + y = -2 thì :

-x + y = -2 + 0 = -2

Nếu x + (-y) = 2 thì :

x + (-y) = 0 + (-2) = -2

Khi x + y = 2 thì ta chỉ có 1 trường hợp là x + y = 2

Nếu x + y = 2 ta có : 

x + y = 1 + 1 = 0 + 2 = 2 + 0 = 2

Trong các trường hợp trên có 6 kết quả 

Vậy số cặp thỏa mãn là 6

Tick nha

\(x\times\frac{3}{5}+x\times\frac{2}{7}=\frac{31}{70}\)

\(x\times\left(\frac{3}{5}+\frac{2}{7}\right)=\frac{31}{70}\)

\(x\times\frac{31}{35}=\frac{31}{70}\)

\(x=\frac{31}{70}:\frac{31}{35}\)

\(x=\frac{1}{2}\)

1/2 BAN NHA 

TA LẤY X*(3/5+2/7)=31/70

X*31/35=31/70

X=31/70:31/35

X=1/2

1/2

ban nhe

tk nhe

xin do