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a: \(\Leftrightarrow-2x=-\dfrac{1}{3}-\dfrac{1}{8}-\dfrac{5}{7}=-\dfrac{197}{168}\)
hay x=197/336
c: \(\Leftrightarrow5x=9+\dfrac{6}{18}-\dfrac{2}{7}=\dfrac{190}{21}\)
hay x=38/21
b: \(\dfrac{5}{7}-\dfrac{2}{3}\cdot x=\dfrac{4}{5}\)
=>\(\dfrac{2}{3}x=\dfrac{5}{7}-\dfrac{4}{5}=\dfrac{25-28}{35}=\dfrac{-3}{35}\)
=>\(x=-\dfrac{3}{35}:\dfrac{2}{3}=\dfrac{-3}{35}\cdot\dfrac{3}{2}=-\dfrac{9}{70}\)
c: \(\dfrac{1}{2}x+\dfrac{3}{5}x=-\dfrac{2}{3}\)
=>\(x\left(\dfrac{1}{2}+\dfrac{3}{5}\right)=-\dfrac{2}{3}\)
=>\(x\cdot\dfrac{5+6}{10}=\dfrac{-2}{3}\)
=>\(x\cdot\dfrac{11}{10}=-\dfrac{2}{3}\)
=>\(x=-\dfrac{2}{3}:\dfrac{11}{10}=-\dfrac{2}{3}\cdot\dfrac{10}{11}=\dfrac{-20}{33}\)
d: \(\dfrac{4}{7}\cdot x-x=-\dfrac{9}{14}\)
=>\(\dfrac{-3}{7}\cdot x=\dfrac{-9}{14}\)
=>\(\dfrac{3}{7}\cdot x=\dfrac{9}{14}\)
=>\(x=\dfrac{9}{14}:\dfrac{3}{7}=\dfrac{9}{14}\cdot\dfrac{7}{3}=\dfrac{3}{2}\)
a) 45 - 3x = 15 b) 4x - 20 = 32 c) 2x : 16 = 14 d) 0 : 5x = 0
3x = 45 - 15 4x = 32 + 20 2x = 14 x 16 Vì 0 chia cho bất cứ số nào
3x = 30 4x = 52 2x = 224 cũng bằng 0 nên suy ra x thuộc Z
x = 30 : 3 x = 52 : 4 x = 224 : 2
x = 10 x = 13 x = 112
e) 3240 : 9x = 18 f) [ 1824 - ( 526 + 2x ) ] + 318 =1420 Câu g) tương tự như câu f)
9x = 3240 : 18 1824 - (526 + 2x) = 1420 - 318
9x = 180 1824 - (526 + 2x) = 1102
x = 180 : 90 526 + 2x = 1824 - 1102
x = 20 526 + 2x = 722
2x = 722 - 526
2x = 196
x = 196 : 2
x = 98
a) I2x-5I=13
<=> 2x-5=13 hoặc 2x-5=-13
<=> 2x=18 hoặc 2x=-8
<=> x=9 hoặc x=-4
b) I7x+3I=66
<=> 7x+3=66 hoặc 7x+3=-66
<=> 7x=63 hoặc 7x=-69
<=> x=9 hoặc x=\(\frac{-69}{7}\)
a) \(\left|2x-5\right|=13\)
\(\Leftrightarrow2x-5=\pm13\)
\(\Leftrightarrow\orbr{\begin{cases}2x-5=13\\2x-5=-13\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=18\\2x=-8\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=9\\2x=-4\end{cases}}}\)
Vậy \(x\in\left\{9;-4\right\}\)
b) \(\left|7x+3\right|=66\)
\(\Leftrightarrow7x+3=\pm66\)
\(\Leftrightarrow\orbr{\begin{cases}7x+3=66\\7x+3=-66\end{cases}\Leftrightarrow\orbr{\begin{cases}7x=63\\7x=-69\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=9\\x=\frac{-69}{7}\end{cases}}}\)
Vậy \(x\in\left\{9;\frac{-69}{7}\right\}\)
a) \(\left|2x-5\right|+5=2x\)
\(\left|2x-5\right|=2x-5\)
\(\Rightarrow2x-5>0\Rightarrow x\ge2,5\)
Vậy \(x\inℝ;x\ge2,5\)
b) \(\left|7x+3\right|=66-x\)
Khi \(\left|7x+3\right|=7x+3\)thì \(x\ge\frac{-3}{7}\)
\(\Rightarrow7x+3=66-x\)
\(7x+x=66-3\)
\(8x=63\)
\(x=\frac{63}{8}\)
Vậy \(x=\frac{63}{8}\)
c) \(\left|5x-2\right|\le2\)
Khi \(\left|5x-2\right|=2\Rightarrow\orbr{\begin{cases}x=0\\x=0,8\end{cases}}\)
Khi \(\left|5x-2\right|=1\Rightarrow\orbr{\begin{cases}x=0,6\\x=0,2\end{cases}}\)
Khi \(\left|5x-2\right|=0\Rightarrow x=0,4\)
Vậy \(x\in\left\{0;0,8;0,6;0,2;0,4\right\}\)
Vì \(x+31⋮x\Rightarrow5.\left(31+x\right)⋮x\Rightarrow155+5x⋮x\)
\(\Rightarrow150+\left(5x+5\right)⋮x\)\(\Rightarrow150⋮x\)\(\Rightarrow x\inƯ\left(150\right)\)
Vậy...................
a ) 5x - 32 = 48
5x = 48 + 32
5x = 80
x = 80 : 5
x = 16
b ) 215 - ( 2x + 143 ) = 16
( 2x + 143 ) = 215 - 16
( 2x + 143 ) = 199
2x = 199 -143
2x = 56
x = 56 : 2
x = 28
bài c hình như sai đề rồi bạn
a)5x=48+32
5x=80
x=16
vay x=16