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a) 2x²-3=29
2x²=32
x²=16
=>x=±4
b)-6x-(-7)=25
=>-6x=18
=>x=-3
c)46-(x-11)=-48
=> x-11=46+48
=>x-11=94
=>x=94+11=105
a) 2 . x2 - 3 = 29
= 2 . x2 = 29 + 3 = 32
= x2 = 32 : 2 = 16
= x2 = 42 ; -42
= x = 4 ; -4
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-12 .( x - 5 ) + 7 .( 3 - x ) = 5
-12x - ( -60 ) + 21 - 7x = 5
-12x + 60 + 21 - 7x = 5
( -12x - 7x ) + ( 60 + 21 ) = 5
-19x + 81 = 5
-19x = 5 - 81
-19x = -76
x = ( -76 ) : ( -19 )
x = 4
\(-5< x< 1\)
\(\Rightarrow\left\{-4;-3;-2;-1;0\right\}\)
Hok tốt
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\(1.\left(x-2\right).\left(x+14\right)=0\)
<=>\(\orbr{\begin{cases}x-2=0\\x+14=0\end{cases}}\)
<=>\(\orbr{\begin{cases}x=2\\x=-14\end{cases}}\)
\(2.\left(x-2\right).\left(x+4\right)=0\)
<=>\(\orbr{\begin{cases}x-2=0\\x+4=0\end{cases}}\)
<=>\(\orbr{\begin{cases}x=2\\x=-4\end{cases}}\)
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\(a,3x-75=45+3.\left(-25\right)\)
\(3x-75=-30\)
\(3x=45\)
\(x=15\)
\(b,2.\left(-7\right)-11=6x+17\)
\(-14-11-17=6x\)
\(-42=6x\)
\(-7=x\Leftrightarrow x=-7\)
\(d,-4.|x-3|=-48\)
\(|x-3|=12\)
\(\Rightarrow\orbr{\begin{cases}x-3=12\\x-3=-12\end{cases}\Rightarrow\orbr{\begin{cases}x=15\\x=-9\end{cases}}}\)
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1) ( x - 2 ) . ( x + 15 ) = 0
\(\Rightarrow\) x - 2 = 0 hoặc x + 15 = 0
* Nếu x - 2 = 0
x = 0 + 2
x = 2
* Nếu x + 15 = 0
x = 0 - 15
x = -15
Vậy x \(\in\) { 2 ; -15 }
2) ( 7 - x ) . ( x + 19 ) = 0
\(\Rightarrow\) 7 - x = 0 hoặc x + 19 = 0
* Nếu 7 - x = 0
x = 7 - 0
x = 7
* Nếu x + 19 = 0
x = 0 - 19
x = -19
Vậy x \(\in\) {7 ; -19}
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a) 3x - 75 = 45 + 3(-25)
=> 3x - 75 = 45 - 75
=> 3x = 45 - 75 + 75
=> 3x = 45
=> x = 45 : 3
=> x = 15
b) 2(-7) - 11 = 6x + 17
=> -14 - 11 = 6x + 17
=> -25 = 6x + 17
=> 6x = -25 - 17
=> 6x = -42
=> x = -42 : 6
=> x = -7
c) |x + 2| = 5
=> \(\orbr{\begin{cases}x+2=5\\x+2=-5\end{cases}}\)
=> \(\orbr{\begin{cases}x=3\\x=-7\end{cases}}\)
Vậy ..
d) -4.|x - 3| = -48
=> |x - 3| = -48 : (-4)
=> |x - 3| = 12
=> \(\orbr{\begin{cases}x-3=12\\x-3=-12\end{cases}}\)
=> \(\orbr{\begin{cases}x=15\\x=-9\end{cases}}\)
Vậy ...
a/\(2\cdot x^2-3=29\)
\(2\cdot x^2=29+3=32\)
\(x^2=\frac{32}{2}=16\)
=> \(x=\sqrt{16}=4\)
b/\(\left(-6\right)x-\left(-7\right)=25\)
\(\left(-6\right)x+7=25\)
\(\left(-6\right)x=25-7=18\)
\(x=\frac{18}{-6}=-3\)
c/ \(46-\left(x-11\right)=-48\)
\(46-x+11=-48\)
\(x=46-\left[\left(-48\right)-11\right]=105\)
a) 2x^2 -3= 29
2x^2 = 32
x^2 = 16
x = +4 ; -4
b) -6x - (-7) =25
-6x +7 =25
-6x = 18
x = -3
c) 46 - (x-11) = -48
46 -x +11 = -48
46 -x = -59
x = 105