a) \(\dfrac{1}{7}< \dfrac{x}{35}< \dfrac{2}{5}\)

\(\Rightarrow\dfrac{5}{35}< \dfrac{x}{35}< \dfrac{14}{35}\)

\(\Rightarrow5< x< 14\)

b) \(\dfrac{5}{13}< 2-x< \dfrac{5}{8}\)

\(\Rightarrow2-\dfrac{5}{8}< x< 2-\dfrac{5}{13}\)

\(\Rightarrow\dfrac{11}{8}< x< \dfrac{21}{13}\)

ai mần tr mình cho tích

a) ta có:\(\dfrac{1}{7}=\dfrac{1.5}{7.5}=\dfrac{5}{35}\);\(\dfrac{2}{5}=\dfrac{2.7}{5.7}=\dfrac{14}{35}\)

\(\Rightarrow x\in\left\{6;7;8;9;10;11;12;13\right\}\)

b)ta có:\(2-x=\dfrac{5}{9};\dfrac{5}{10};\dfrac{5}{11};\dfrac{5}{12}\)

\(\Rightarrow x=2-\dfrac{5}{9};2-\dfrac{5}{10};2-\dfrac{5}{11};2-\dfrac{5}{12}\)

\(\Rightarrow x=\dfrac{13}{9};\dfrac{3}{2};\dfrac{17}{11};\dfrac{19}{12}\)

-526 chuan 100% luon

nho nhá

-526 chuẩn 100% luôn 

nho

x + (-405) , mà x = -121

suy ra x = (-121) + (-405)

x= -(121+405)

x= -526

vậy x = -526

X + ( - 405 ) = ?

Biết

X = -121

( -121 ) + ( -405 ) = -526

AI BẢO BÀU HỒI NÃY NÓI K MÀ KO K BAI NAY BIET NHUNG KO GIAI

a) \(\frac{4}{5}=\frac{28}{35}\)

b) \(\frac{12}{15}=\frac{72}{90}\)

c) \(\frac{125}{300}=\frac{5}{12}\)

d) \(\frac{6}{9}=\frac{36}{54}\)

/HT\

a) \(\frac{4}{5}=\frac{28}{35}\)      \(\text{X}=28\)

b) \(\frac{12}{15}=\frac{72}{90}\)   \(\text{X}=90\)

c) \(\frac{125}{300}=\frac{5}{12}\)  \(\text{X}=12\)

d) \(\frac{6}{9}=\frac{36}{54}\)       \(\text{X}=6\)

\(a,\)\(\frac{4}{5}=\frac{X}{35}\)

\(\Rightarrow\)\(X=35\times\frac{4}{5}\)

\(\Rightarrow\)\(X=28\)

\(b,\)\(\frac{12}{15}=\frac{72}{X}\)

\(\Rightarrow\)\(X=72\div\frac{12}{15}\)

\(\Rightarrow\)\(X=90\)

\(c,\)\(\frac{125}{300}=\frac{5}{X}\)

\(\Rightarrow\)\(\frac{5}{12}=\frac{5}{X}\)

\(\Rightarrow\)\(X=12\)

\(d,\)\(\frac{X}{9}=\frac{36}{54}\)

\(\Rightarrow\)\(\frac{X}{9}=\frac{6}{9}\)

\(\Rightarrow\)\(X=6\)

-25-(x+5) = 415 + 5(x-83)

=> -25-x-5=415+5x-415

=> -30-x-5x = 0

=> -30=6x

=> x = -5 

`-25-(x+5)=415+5(x-83)`

`<=> -25-x-5=415+5x-415`

`<=> -x-5x=415-415+25+5`

`<=> -6x=30`

`<=> x=-5`

-25 - ( x+5 ) = 415 + 5(x- 83)

\(-25-x-5-415-5x+415=0\)

\(-30-6x=0\)

\(6x=-30\)

\(x=-30:6=-5\)

Vậy x=-5

Ta có : (x - 5)(x² + 2) = 0 

Vì x² + 2 \(\ge0\forall x\in N\)

Nên : x - 5 = 0 

=> x = 5

b) Ta có : x + 5 = |x| - 5

=> |x| = x + 5 + 5

=> |x| = x + 10

\(\Leftrightarrow\hept{\begin{cases}x=x+10\\-x=x+10\end{cases}}\)

\(\Leftrightarrow\hept{\begin{cases}x-x-10=0\left(\text{ vô lý}\right)\\-x-x=10\end{cases}}\)

<=> -2x = 10

=> x = -5

a) \(\left(x-5\right).\left(x^2+2\right)=0\)

\(\Rightarrow\) x - 5 = 0 hoặc x\(^2\)+ 2 = 0

\(\Rightarrow x=0+5\)hoặc x\(^2\)= 0 - 2

\(\Rightarrow\)x = 5 hoặc x\(^2\)= -2 (vô lý vì \(x^2\ge0\)  \(\forall x\))

Vậy : x = 5

b) \(x+5=|x|-5\)

\(\Rightarrow|x|=x+5+5\)

\(\Rightarrow|x|=x+10\)

\(\Rightarrow x=x+10\) (vô lý)     hoặc \(-x=x+10\)

\(\Rightarrow-x-x=10\)

\(\Rightarrow-2x=10\)

\(\Rightarrow x=\frac{10}{-2}=-5\)

Vậy : x = -5

Nhớ kb vs k mik nha!

a,x=1

b,x=13,5

k nha

a)  |x-3|+|7-x|=10
     x-3+7-x=10
     2x-3+7=10
     2x-3    = 10-7
     2x-3    = 3
     2x       = 3+3
     2x       = 6
     x         = 6:2
     x         = 3
Câu 2 tớ chưa nghĩ ra
    
     

a,ta có |x-3|+|x-7|>=|x-3+x-7|=10

bài kia em giải tương tự nhé