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Mình làm câu khó thôi nhé.
2x chia hết cho 3
=>(2x+x-x) chia hết cho 3
=>(3x-x) chia hết cho 3
3x chia hết cho 3=>x chia hết cho 3
=>x thuộc B(3)={0;3;6;...}
Vậy x thuộc {0;3;6;...ư}
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\(\left(-300\right):20+5.\left(3x-1\right)=25\)
\(\Rightarrow-15+15x-5=25\)
\(\Rightarrow-20x+15x=25\)
\(\Rightarrow15x=45\)
\(\Rightarrow x=3\)
( - 300 ) : 20 + 5( 3x -1 ) = 25
- 15 + 5( 3x -1 ) = 25
-15 + 15x -5 = 25
- 20 + 15x = 25
15x - 20 = 25
15x - 20 + 20 = 25 + 20
15x = 25 + 20
15x = 45
15x : 15 = 45 : 15
x = 45 : 15
x = 3
vậy x = 3
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a) \(\left(2x+\frac{3}{5}\right)^2-\frac{9}{25}=0\)
\(\left(2x+\frac{3}{5}\right)^2=\frac{9}{25}\)
\(\left(2x+\frac{3}{5}\right)^2=\left(\frac{3}{5}\right)^2\)
\(=>2x+\frac{3}{5}=\frac{3}{5}\)
\(2x=\frac{3}{5}-\frac{3}{5}\)
\(2x=0\)
\(x=0:2\)
\(x=0\)
b) \(\left(3x-1\right).\left(-\frac{1}{2x}+5\right)=0\)
=> \(\left(3x-1\right)=0\)hoặc \(\left(-\frac{1}{2x}+5\right)=0\)hoặc \(\left(3x-1\right)\)và\(\left(-\frac{1}{2x}+5\right)\)cùng bằng 0.
\(\orbr{\begin{cases}3x-1=0\\-\frac{1}{2x}+5=0\end{cases}}=>\orbr{\begin{cases}3x=1\\-\frac{1}{2x}=-5\end{cases}}=>\orbr{\begin{cases}x\in\varnothing\\2x=\frac{1}{5}\end{cases}}=>x=\frac{1}{5}:2=>x=\frac{1}{10}\)
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a) x - (17 - 8) = 5 + (10 - 3x)
x - 17 + 8 = 5 + 10 - 3x
x + 3x = 5 + 10 + 17 - 8
4x = 24
x = 24 : 4
x = 6
b) 25 - (30 + x) = x - (27 - 8)
25 - 30 - x = x - 27 + 8
-x - x = -27 + 8 - 25 + 30
-2x = -14
x = (-14) : (-2)
x = 7
c) (x - 12) - 15 = (20 - 7) - (18 + x)
x - 12 - 15 = 20 - 7 -18 - x
x + x = 20 - 7 - 18 + 12 + 15
2x = 22
x = 22 : 2
x = 11
d) 9 - 25 = (7 - x) - (25 + 7)
9 - 25 = 7 - x - 25 - 7
x = 7 - 25 - 7 - 9 +25
x = -9
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Tk mình đi mọi người mình bị âm nè!
Ai tk mình mình tk lại cho!!
\(\left(-300\right):20+5.\left(3x-1\right)=25\)
\(\Leftrightarrow-15+5.\left(3x-1\right)=25\)
\(\Leftrightarrow5\left(3x-1\right)=40\)
\(\Leftrightarrow3x-1=8\)
\(\Leftrightarrow3x=9\)
\(\Leftrightarrow x=3\)
Vậy x =3
(-15) + 5.[ 3x - 1] = 25
5.[ 3x - 1] = 25 - (-15)
5.[ 3x - 1] = 25 + 15
5.[ 3x - 1] = 40
3x - 1 = 40 : 5
3x - 1 = 8
3x = 8+ 1
3x = 9
x = 9:3
x =3
Vậy x = 3 HT nha