Tìm số nguyên x biết:
a) 15 – ( 4 – x) = 6 ;
b) - 30 + ( 25 – x) = - 1 ;
c) x – ( 12 – 25) = -8 ;
d) ( x – 29 ) – ( 17 – 38 ) = - 9
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a) 4 . x + 15 = - 5
⇒ 4 . x = - 5 – 15
⇒ 4 . x = - 20
⇒ x = - 20 : 4
⇒ x = - 5.
Vậy x = - 5.
b) (- 270) : x – 20 = 70.
⇒ (- 270) : x = 70 + 20
⇒ (- 270) : x = 90
⇒ x = (- 270) : 90
⇒ x = - 3
Vậy x = - 3
a,-4/7=x/21
-12/21 = x/21
x= -12
b,(x-3)/15=1/-5
x - 3 = -1/5 * 15
x - 3 = -3
x = 0
c,.(3x+8)/-12=-5/30
=> 3x + 8 = 2
=> 3x=-6
=>x=-2
a) Ta có: 12-5x=37
\(\Leftrightarrow5x=-25\)
hay x=-5
Vậy: x=-5
b) Ta có: 7-3|x-2|=-11
\(\Leftrightarrow3\left|x-2\right|=18\)
\(\Leftrightarrow\left|x-2\right|=6\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=6\\x-2=-6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-4\end{matrix}\right.\)
Vậy: \(x\in\left\{8;-4\right\}\)
c) Ta có: \(x+\dfrac{2}{8}=-\dfrac{15}{4}\)
\(\Leftrightarrow x=\dfrac{-15}{4}-\dfrac{2}{8}=\dfrac{-15}{4}-\dfrac{1}{4}\)
hay x=-4
Vậy: x=-4
a, \(\Leftrightarrow5x=12-37=-25\)
\(\Leftrightarrow x=-\dfrac{25}{5}=-5\)
Vậy ...
b, \(\Leftrightarrow3\left|x-2\right|=7+11=18\)
\(\Leftrightarrow\left|x-2\right|=\dfrac{18}{3}=6\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=6\\x-2=-6\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-4\end{matrix}\right.\)
Vậy ...
c, \(\Leftrightarrow x=-\dfrac{15}{4}-\dfrac{2}{8}=-4\)
Vậy ..
a)\(\dfrac{4}{x}=\dfrac{x}{16}\)
<=>\(x^2=4.16=64\)
<=>\(x=\pm8\)
<=>x=-8(vì x<0)
b)\(\dfrac{x}{-24}=\dfrac{-6}{x}\)
<=>\(x^2=\left(-24\right)\left(-6\right)=144\)
<=>\(x=\pm12\)
<=>x=12(Vì x>0)
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
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, \(\dfrac{42}{-54}=-\dfrac{42}{6x}\Rightarrow6x=54\Leftrightarrow x=9\)
a) 15 – ( 4 – x) = 6
=> 4 – x= 15 - 6
=> 4 – x= 9
=> x= 4 - 9
=> x= -5
Easy!
a) \(15-\left(4-x\right)=6\)
\(\Leftrightarrow4-x=15-6\)
\(\Leftrightarrow4-x=9\)
\(\Leftrightarrow x=4-9\)
\(\Leftrightarrow x=-5\)
Vậy \(x=-5\)
b) \(-30+\left(25-x\right)=-1\)
\(\Leftrightarrow\left(25-x\right)=-1-\left(-30\right)\)
\(\Leftrightarrow25-x=29\)
\(\Leftrightarrow x=25-29\)
\(\Leftrightarrow x=-4\)
c) \(x-\left(12-25\right)=-8\)
\(\Leftrightarrow x-\left(-13\right)=-8\)
\(\Leftrightarrow x=-8+-13\)
\(\Leftrightarrow x=-21\)
Vậy \(x=-21\)
d) \(\left(x-29\right)-\left(17-38\right)=-9\)
\(\Leftrightarrow\left(x-29\right)-\left(-21\right)=-9\)
\(\Leftrightarrow x-29=-9+\left(-21\right)\)
\(\Leftrightarrow x-29=-30\)
\(\Leftrightarrow x=-30+29\)
\(\Leftrightarrow x=-1\)
Vậy \(x=-1\)