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tim x biet
2/3x^2-5x+2 + 13/3x^2+x+2 = 6/x
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1) 5x = 120 : 2
5x = 60
x = 60 : 5
x = 12.
2) 3x + 27 = 45
3x = 45 - 27
3x = 18
x = 18 : 3
x = 6.
3) 73 + x - 122 = 234 : 2
73 + x - 122 = 117
73 + x = 117 + 122
73 + x = 239
x = 239 - 73
x = 166.
4) 32 - 2 ( x - 1 ) = 12
2 ( x - 1 ) = 32 - 12
2 ( x - 1 ) = 20
x - 1 = 20 : 2
x - 1 = 10
x = 10 + 1
x = 11.
5) 3 ( x + 1 ) - 15 = 36
3 ( x + 1 ) = 36 + 15
3 ( x + 1 ) = 51
x + 1 = 51 : 3
x + 1 = 17
x = 17 - 1
x = 16.
6) 32 - ( 4x - 16 ) = 21
4x - 16 = 32 - 21
4x - 16 = 11
4x = 11 + 16
4x = 27
x = 27 : 4
x = 6,75.
7) 13x - 3x = 500
( 13 - 3 )x = 500
10x = 500
x = 500 : 10
x = 50.
8) 9x + x - 35 = 68
9x + 1x - 35 = 68
9x + 1x = 68 + 35
9x + 1x = 103
( 9 + 1 )x = 103
10x = 103
x = 103 : 10
x = 10,3.
1) 5x = 120 : 2
5x = 60
x = 60 : 5
x = 12.
2) 3x + 27 = 45
3x = 45 - 27
3x = 18
x = 18 : 3
x = 6.
3) 73 + x - 122 = 234 : 2
73 + x - 122 = 117
73 + x = 117 + 122
73 + x = 239
x = 239 - 73
x = 166.
4) 32 - 2 ( x - 1 ) = 12
2 ( x - 1 ) = 32 - 12
2 ( x - 1 ) = 20
x - 1 = 20 : 2
x - 1 = 10
x = 10 + 1
x = 11.
5) 3 ( x + 1 ) - 15 = 36
3 ( x + 1 ) = 36 + 15
3 ( x + 1 ) = 51
x + 1 = 51 : 3
x + 1 = 17
x = 17 - 1
x = 16.
6) 32 - ( 4x - 16 ) = 21
4x - 16 = 32 - 21
4x - 16 = 11
4x = 11 + 16
4x = 27
x = 27 : 4
x = 6,75.
7) 13x - 3x = 500
( 13 - 3 )x = 500
10x = 500
x = 500 : 10
x = 50.
8) 9x + x - 35 = 68
9x + 1x - 35 = 68
9x + 1x = 68 + 35
9x + 1x = 103
( 9 + 1 )x = 103
10x = 103
x = 103 : 10
x = 10,3.
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 \(x\in\left\{9;\frac{-69}{7}\right\}\)
\(a,\left(x-2\right)^2-\left(x-3\right)\left(x^2+3x+9\right)+6\left(x+1\right)^2=15\)\(\Leftrightarrow x^3-6x^2+12x-8-x^3+27+6\left(x^2+2x+1\right)=15\)\(\Leftrightarrow-6x^2+12x+19+6x^2+12x+6=15\)
\(\Leftrightarrow24x=-10\)
\(\Leftrightarrow x=-\dfrac{5}{12}\)
Vậy:....
\(b,\left(5x+1\right)^2-\left(5x+3\right)\left(5x-3\right)=30\)
\(\Leftrightarrow25x^2+10x+1-25^2+9=30\)
\(\Leftrightarrow10x=20\)
\(\Rightarrow x=2\)
Vậy :....
\(c,\left(x+3\right)\left(x^2-3x+9\right)-x\left(x-2\right)\left(x+2\right)=15\)\(\Leftrightarrow x^3+27-x\left(x^2-4\right)=15\)
\(\Leftrightarrow x^3+27-x^3+4x=15\)
\(\Leftrightarrow4x=15-27=-12\)
\(\Leftrightarrow x=-3\)
vậy : .....
a) 5x = 120 : 2
5x = 60
x = 60 : 5
x = 12
b) 3x + 27 = 45
3x = 45 - 27
3x = 18
x = 18 : 3
x = 6
c) 73 + x - 122 = 234 : 2
73 + x - 122 = 117
73 + x = 117 + 122
73 + x = 239
x = 239 - 73
x = 166
d) 32 - 2(x - 1) = 12
2(x - 1) = 32 - 12
2(x - 1) = 20
x - 1 = 20 : 2
x - 1 = 10
x = 10 + 1
x = 11
e) 3(x + 1) - 15 = 36
3(x + 1) = 36 + 15
3(x + 1) = 51
x + 1 = 51 : 3
x + 1 = 17
x = 17 - 1
x = 16
f) 21 - (4x - 16) = 21
4x - 16 = 21 - 21
4x - 16 = 0
4x = 0 + 16
4x = 16
x = 16 : 4
x = 4
g) 13x - 3x = 500
10x = 500
x = 500 : 10
x = 50
h) 9x + x - 35 = 65
10x - 35 = 65
10x = 65 + 35
10x = 100
x = 100 : 10
x = 10