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27 tháng 6 2017
a) \(\left(x-1\right):3=2^3\) \(\Leftrightarrow\) \(\left(x-1\right):3=8\) \(x+1=24\) \(\Leftrightarrow\) \(x=23\) vậy \(x=23\)
b) \(12-2\left(x+5\right)=-10\) \(\Leftrightarrow\) \(12-2x-10=-10\)
\(\Leftrightarrow\) \(-2x=-12\) \(\Leftrightarrow\) \(x=6\) vậy \(x=6\)
c) \(x-12\left(x+5\right)=-10\) \(\Leftrightarrow\) \(x-12x-60=-10\)
\(\Leftrightarrow\) \(-11x=50\) \(\Leftrightarrow\) \(x=\dfrac{50}{-11}\) vậy \(x=\dfrac{50}{-11}\)
e) \(13-x:2=10\Leftrightarrow-x:2=-3\Leftrightarrow x=\dfrac{3}{2}\)
f) \(\left|12-x\right|-7=5\)
th1 : \(x\le12\) thì \(\left|12-x\right|-7=5\) \(\Leftrightarrow\) \(12-x-7=5\) \(\Leftrightarrow\) \(-x=0\Leftrightarrow x=0\)
th2 : \(x>12\) thì \(\left|12-x\right|-7=5\) \(\Leftrightarrow\) \(x-12-7=5\) \(\Leftrightarrow\) \(x=24\) vậy \(x=0;x=24\)
i) \(x^2-7=2\Leftrightarrow x^2=9\Leftrightarrow x=3\) vậy \(x=3\)
k) \(x^3-4=-12\) \(\Leftrightarrow\) \(x^3=-8\) \(\Leftrightarrow x=-2\) vậy \(x=-2\)
27 tháng 6 2017
a)\(\left(x-1\right):3=2^3\Rightarrow x-1=2^3.3=24\Rightarrow x=25\)
b)\(12-2\left(x+5\right)=-10\Leftrightarrow12-2x-10=-10\Rightarrow2-2x=-10\Rightarrow2x=12\Rightarrow x=6\)c)\(x-12\left(x+5\right)=-10\Rightarrow x-12x-60=-10\Rightarrow-11x-60=-10\Rightarrow-11x=-70\Rightarrow x=\dfrac{70}{-11}\)d)\(6-\left|x\right|=5\Rightarrow\left|x\right|=1\Rightarrow x=\left\{\pm1\right\}\)
Làm nốt nha
27 tháng 6 2019
\(a,\frac{1}{2}+\frac{2}{3}x=\frac{4}{5}\)
=> \(\frac{2}{3}x=\frac{4}{5}-\frac{1}{2}=\frac{3}{10}\)
=> \(x=\frac{3}{10}:\frac{2}{3}=\frac{9}{20}\)
Vậy \(x\in\left\{\frac{9}{20}\right\}\)
\(b,x+\frac{1}{4}=\frac{4}{3}\)
=> \(x=\frac{4}{3}-\frac{1}{4}=\frac{13}{12}\)
Vậy \(x\in\left\{\frac{13}{12}\right\}\)
\(c,\frac{3}{5}x-\frac{1}{2}=-\frac{1}{7}\)
=> \(\frac{3}{5}x=-\frac{1}{7}+\frac{1}{2}=\frac{5}{14}\)
=> \(x=\frac{5}{14}:\frac{3}{5}=\frac{25}{42}\)
Vậy \(x\in\left\{\frac{25}{42}\right\}\)
\(d,\left|x+5\right|-6=9\)
=> \(\left|x+5\right|=9+6=15\)
=> \(\left[{}\begin{matrix}x+5=15\\x+5=-15\end{matrix}\right.\)
=> \(\left[{}\begin{matrix}x=15-5=10\\x=-15-5=-20\end{matrix}\right.\)
Vậy \(x\in\left\{10;-20\right\}\)
\(e,\left|x-\frac{4}{5}\right|=\frac{3}{4}\)
=> \(\left[{}\begin{matrix}x-\frac{4}{5}=\frac{3}{4}\\x-\frac{4}{5}=-\frac{3}{4}\end{matrix}\right.\)
=> \(\left[{}\begin{matrix}x=\frac{3}{4}+\frac{4}{5}=\frac{31}{20}\\x=-\frac{3}{4}+\frac{4}{5}=\frac{1}{20}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{31}{20};\frac{1}{20}\right\}\)
\(f,\frac{1}{2}-\left|x\right|=\frac{1}{3}\)
=> \(\left|x\right|=\frac{1}{2}-\frac{1}{3}\)
=> \(\left|x\right|=\frac{1}{6}\)
=> \(\left[{}\begin{matrix}x=\frac{1}{6}\\x=-\frac{1}{6}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{1}{6};-\frac{1}{6}\right\}\)
\(g,x^2=16\)
=> \(\left|x\right|=\sqrt{16}=4\)
=> \(\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)
vậy \(x\in\left\{4;-4\right\}\)
\(h,\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)
=> \(x-\frac{1}{2}=\sqrt[3]{\frac{1}{27}}=\frac{1}{3}\)
=> \(x=\frac{1}{3}+\frac{1}{2}=\frac{5}{6}\)
Vậy \(x\in\left\{\frac{5}{6}\right\}\)
\(i,3^3.x=3^6\)
\(x=3^6:3^3=3^3=27\)
Vậy \(x\in\left\{27\right\}\)
\(J,\frac{1,35}{0,2}=\frac{1,25}{x}\)
=> \(x=\frac{1,25.0,2}{1,35}=\frac{5}{27}\)
Vậy \(x\in\left\{\frac{5}{27}\right\}\)
\(k,1\frac{2}{3}:x=6:0,3\)
=> \(\frac{5}{3}:x=20\)
=> \(x=\frac{5}{3}:20=\frac{1}{12}\)
Vậy \(x\in\left\{\frac{1}{12}\right\}\)
15 tháng 6 2018
\(\frac{1}{3}x+\frac{2}{5}\left(x-1\right)=0\)
\(\Leftrightarrow\frac{1}{3}x+\frac{2}{5}x-\frac{2}{5}=0\)
\(\Leftrightarrow\frac{11}{15}x=\frac{2}{5}\)
\(\Leftrightarrow x=\frac{2}{5}\div\frac{11}{15}=\frac{2.15}{5.11}=\frac{6}{11}\)
Vậy x = 6/11
15 tháng 6 2018
a) \(\frac{1}{3}.x+\frac{2}{5}.\left(x-1\right)=0\)
\(\frac{1}{3}.x+\frac{2}{5}.x-\frac{2}{5}=0\)
\(x.\left(\frac{1}{3}+\frac{2}{5}\right)-\frac{2}{5}=0\)
\(x.\frac{11}{15}-\frac{2}{5}=0\)
\(x.\frac{11}{15}=\frac{2}{5}\)
\(x=\frac{2}{5}:\frac{11}{15}\)
\(x=\frac{6}{11}\)
b) \(3.\left(x-\frac{1}{2}\right)-5.\left(x+\frac{3}{5}\right)=x+\frac{1}{5}\)
\(3x-\frac{3}{2}-5x-3=x+\frac{1}{5}\)
\(3x-5x-\left(\frac{3}{2}+3\right)=x+\frac{1}{5}\)
\(-2x-\frac{9}{2}=x+\frac{1}{5}\)
\(\Rightarrow-2x-x=\frac{1}{5}+\frac{9}{2}\)
\(-3x=\frac{47}{10}\)
\(x=\frac{47}{10}:\left(-3\right)\)
\(x=\frac{-47}{30}\)
HH
15 tháng 6 2018
Giải:
a) \(\dfrac{1}{3}x+\dfrac{2}{5}\left(x-1\right)=0\)
\(\Leftrightarrow\dfrac{1}{3}x+\dfrac{2}{5}x-\dfrac{2}{5}=0\)
\(\Leftrightarrow\dfrac{11}{15}x-\dfrac{2}{5}=0\)
\(\Leftrightarrow\dfrac{11}{15}x=\dfrac{2}{5}\)
\(\Leftrightarrow x=\dfrac{6}{11}\)
Vậy ...
b) \(3\left(x-\dfrac{1}{2}\right)-5\left(x+\dfrac{3}{5}\right)=x+\dfrac{1}{5}\)
\(\Leftrightarrow3x-\dfrac{3}{2}-5x-3=x+\dfrac{1}{5}\)
\(\Leftrightarrow-2x-\dfrac{9}{2}=x+\dfrac{1}{5}\)
\(\Leftrightarrow-3x=\dfrac{47}{10}\)
\(\Leftrightarrow x=\dfrac{-47}{30}\)
Vậy ...
15 tháng 6 2018
a, 1/3 . x + 2/5 . ( x - 1 ) = 0
1/3 . x + 2/5 . x - 2/5 = 0
x . ( 1/3 + 2/5 ) = 0 + 2/5
x . 11/15 = 2/5
x = 2/5 : 11/15
x = 6/11
b, 3 . ( x - 1/2 ) - 5 . ( x + 3/5 ) = x + 1/5
3 . x - 3 . 1/2 - 5 . x + 5. 3/5 = x + 1/5
3x - 3/2 - 5x + 3 = x + 1/5
3x - 5x + x = 1/5 + 3/2 - 3
-3x = -13/10
x = -13/10 : -1
x = -13/10
18 tháng 2 2020
\(a,234-\left(x-56\right)=789\)
\(\Leftrightarrow x-56=234-789\)
\(\Leftrightarrow x-56=-555\)
\(\Leftrightarrow x=\left(-555\right)+56=-499\)
Vậy x = -499
b) \(\frac{x+3}{-5}=\frac{x-15}{4}\)
\(\Leftrightarrow4\left(x+3\right)=-5\left(x-15\right)\)
\(\Leftrightarrow4x+12=-5x+75\)
\(\Leftrightarrow4x+12-\left(-5x\right)=75\)
\(\Leftrightarrow4x-\left(-5x\right)+12=75\)
\(\Leftrightarrow4x+5x=63\)
\(\Leftrightarrow9x=63\)
\(\Leftrightarrow x=7\)
Vậy x = 7
c) \(8\left(x-1\right)-7=2\left(x+2\right)+5\)
\(\Leftrightarrow8x-8-7=2x+4+5\)
\(\Leftrightarrow8x-8-7-2x+4=5\)
\(\Leftrightarrow8x-2x-8-7+4=5\)
\(\Leftrightarrow8x-2x=5-4+7+8\)
\(\Leftrightarrow4x=16\)
\(\Leftrightarrow x=4\)
Vậy x = 4
d) Đặt \(D=\frac{2x+3}{x-1}=\frac{2x-2+5}{x-1}=\frac{2\left(x-1\right)+5}{x-1}=2+\frac{5}{x-1}\)
=> \(5⋮x-1\)
=> \(x-1\inƯ\left(5\right)\)
=> \(x-1\in\left\{\pm1;\pm5\right\}\)
=> \(x\in\left\{2;0;6;-4\right\}\)
4 tháng 1 2017
a ) + ) Xét x \(\ge\) 3 => |x - 3| = x - 3
=> |x - 3| + x - 3 = x - 3 + x - 3 = 0
<=> 2x - 6 = 0
<=> 2x = 6
=> x = 3
+ ) Xét x < 3 => |x - 3| = 3 - x
=> |x - 3| + x - 3 = 3 - x + x - 3 = 0
<=> 0 = 0 ( loại )
Vậy x = 3
ý khác tương tự
28 tháng 6 2017
a) x-12:(-2)=4
=> x-12=-8
=> x=4
b ) 6-|x| = 5
=> /x/=1
=> x=1;-1
c ) 7⋮ ( x-3)
=> (x-3) thuộc Ư(7)
=> x-3=1 => x=4
=> x-3=-1 => x=2
=> x-3=7 => x= 10
=> x-3=-7 => x=-4
d ) 3⋮ ( 2x+1 )
=> (2x+1) thuộc Ư(3)
=> (2X+1)= 1 => x= 0
=> (2x+1)=-1 => x= -1
=> 2x+1= 3 => x= 1
=> 2x+1=-3 => x= -2
28 tháng 6 2017
a) \(x-12:\left(-2\right)=4\Rightarrow x-\left(-6\right)=4\Rightarrow x=\left(-6\right)+4=-2\)
b) \(6-\left|x\right|=5\Rightarrow\left|x\right|=6-5=1\Rightarrow x=\left\{\pm1\right\}\)
c)\(7⋮x-3\Rightarrow x-3\inƯ\left(7\right)\)
\(Ư\left(7\right)=\left\{\pm1;\pm7\right\}\)
\(x=\left\{4;2;10;-4\right\}\)
d) \(3⋮2x+1\Rightarrow2x+1\inƯ\left(3\right)\)
\(Ư\left(3\right)=\left\{\pm1;\pm3\right\}\)
\(x\in\left\{0;-1;1;-2\right\}\)
6 tháng 2 2020
Câu 3 : Bài giải
\(5x+47y=5\left(x+6y\right)+17y\text{ }⋮\text{ }17\)
\(\Rightarrow\text{ }5\left(x+6y\right)\text{ }⋮\text{ }17\) mà \(5⋮̸17\) nên \(x+6y\text{ }⋮\text{ }17\)
\(\Rightarrow\text{ ĐPCM}\)
\(\dfrac{2}{3}x+x=\dfrac{1}{5}\)
=>\(x\left(\dfrac{2}{3}+1\right)=\dfrac{1}{5}\)
=>\(x\cdot\dfrac{5}{3}=\dfrac{1}{5}\)
=>\(x=\dfrac{1}{5}:\dfrac{5}{3}=\dfrac{3}{25}\)
\(\frac23x+x\) \(=\frac15\)
\(\Rightarrow\frac53x=\) \(\frac15\)
\(\Rightarrow x=\frac15:\frac53\) \(=\frac{3}{25}\)