tìm x gì ? x nguyên hay gì ?

Tìm x thuộc Q

#)Giải :

\(\frac{2}{5}< \left|x-\frac{7}{5}\right|< \frac{3}{5}\)

\(\Rightarrow\frac{4}{10}< \left|x-\frac{7}{5}\right|< \frac{6}{10}\)

\(\Rightarrow\left|x-\frac{7}{5}\right|=1\)

\(\orbr{\begin{cases}x-\frac{7}{5}=1\\x-\frac{7}{5}=-1\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{12}{5}\\x=\frac{2}{5}\end{cases}}}\)

Vậy x có hai giá trị : \(x=\frac{12}{5};x=\frac{2}{5}\)

b) | x + 11/2 | > |-5,5| hay 5,5

Xét :

+) x + 11/2 > 5,5

<=> x > 0

+) -x - 11/2 > 5.5

<=> -x > 11 hay x > -11

vậy....

a) | x - 5/3 | > 1/3

Xét :

+) x - 5/3 > 1/3

<=> x > 2 ( tm )

+) -x + 5/3 > 1/3

 <=> -x > -4/3 => x > 4/3 (tm)

Vậy,.....

bạn lm sai ở gần cuối

a)|x-3/5|<1/3

\(\Leftrightarrow\frac{-1}{3}< x-\frac{3}{5}< \frac{1}{3}\)

\(\Leftrightarrow\frac{4}{15}< x< \frac{14}{15}\)

Tương tự :)))

Cái dề, bài này giúp á, tính ra là ok mà

(13/10x - 15).(-5/14) = 3

13/10x - 15 = 3 : (-5/14)

13/10x - 15 = 3 x (-14/5)

13/10x - 15 = -42/5

=> 13/10x = -42/5 + 15

=> 13/10x = 33/5

=> x = 33/5 : 13/10

=> x = 33/5 x 10/13

=> x = 66/13

bn tự lm típ, tính ra là ok mà

a) \(\dfrac{x}{2}=\dfrac{y}{5}=\dfrac{z}{7};x+y+z=56\)

\(\dfrac{x}{2}=\dfrac{y}{5}=\dfrac{z}{7}=\dfrac{x+y+z}{2+5+7}=\dfrac{56}{14}=4\)

\(\Rightarrow\left\{{}\begin{matrix}x=4.2=8\\y=4.5=20\\z=4.7=28\end{matrix}\right.\)

b) \(\dfrac{x}{1,1}=\dfrac{y}{1,3}=\dfrac{z}{1,4}\left(1\right);2x-y=5,5\)

\(\left(1\right)\Rightarrow\dfrac{2x-y}{1,1.2-1,3}=\dfrac{5,5}{0,9}\)

\(\Rightarrow\left\{{}\begin{matrix}x=1,1.\dfrac{5,5}{0,9}=\dfrac{6,05}{0,9}\\y=1,3.\dfrac{5,5}{0,9}=\dfrac{7,15}{0,9}\\z=\dfrac{1,4}{1,1}.x=\dfrac{1,4}{1,1}.\dfrac{6,05}{0,9}=\dfrac{8,47}{0,99}\end{matrix}\right.\)

d) \(\dfrac{x}{2}=\dfrac{x}{3}=\dfrac{z}{5};xyz=-30\)

\(\dfrac{x}{2}=\dfrac{x}{3}=\dfrac{z}{5}=\dfrac{xyz}{2.3.5}=\dfrac{-30}{30}=-1\)

\(\Rightarrow\left\{{}\begin{matrix}x=2.\left(-1\right)=-2\\y=3.\left(-1\right)=-3\\z=5.\left(-1\right)=-5\end{matrix}\right.\)

a) �2=�5=�7;�+�+�=562x​=5y​=7z​;x+y+z=56

�2=�5=�7=�+�+�2+5+7=5614=42x​=5y​=7z​=2+5+7x+y+z​=1456​=4

⇒{�=4.2=8�=4.5=20�=4.7=28⇒⎩⎨⎧​x=4.2=8y=4.5=20z=4.7=28​

b) �1,1=�1,3=�1,4(1);2�−�=5,51,1x​=1,3y​=1,4z​(1);2x−y=5,5

(1)⇒2�−�1,1.2−1,3=5,50,9(1)⇒1,1.2−1,32x−y​=0,95,5​
    

⇒⎩⎨⎧​x=1,1.0,95,5​=0,96,05​y=1,3.0,95,5​=

chết rùi nó bị lỗi

xin lỗi nha

a: |x-3/5|<1/3

=>x-3/5>-1/3 và x-3/5<1/3

=>x>4/15 và x<14/15

=>4/15<x<14/15

b: |x+11/2|>|-5,5|

=>|x+11/2|>11/2

=>x+11/2>11/2 hoặc x+11/2<-11/2

=>x>0 hoặc x<-11