6x mũ 3 + x mũ 2 - 2x = 0
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1, \(3x\left(x-7\right)+2x-14=0\)
\(\Rightarrow3x\left(x-7\right)+2\left(x-7\right)=0\)
\(\Rightarrow\left(x-7\right)\left(3x+2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=7\\x=\frac{-2}{3}\end{cases}}\)
2, \(x^3+3x^2-\left(x+3\right)=0\)
\(\Rightarrow x^2\left(x+3\right)-\left(x+3\right)=0\)
\(\Rightarrow\left(x+3\right)\left(x^2-1\right)=0\)
\(\Rightarrow\left(x+3\right)\left(x-1\right)\left(x+1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=-3\\x=\pm1\end{cases}}\)
3, \(15x-5+6x^2-2x=0\)
\(\Rightarrow\left(15x-5\right)+\left(6x^2-2x\right)=0\)
\(\Rightarrow5\left(3x-1\right)+2x\left(3x-1\right)=0\)
\(\Rightarrow\left(3x-1\right)\left(5+2x\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x-1=0\\5+2x=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{1}{3}\\x=\frac{-5}{2}\end{cases}}\)
4, \(5x-2-25x^2+10x=0\)
\(\Rightarrow\left(5x-25x^2\right)-\left(2-10x\right)=0\)
\(\Rightarrow5x\left(1-5x\right)-2\left(1-5x\right)=0\)
\(\Rightarrow\left(1-5x\right)\left(5x-2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}1-5x=0\\5x-2=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{1}{5}\\x=\frac{2}{5}\end{cases}}\)
3, \(\left(x-2\right)^2-5\left(2-x\right)=0\Leftrightarrow\left(2-x\right)^2-5\left(2-x\right)=0\)
\(\Leftrightarrow\left(2-x-5\right)\left(2-x\right)=0\Leftrightarrow\left(x+3\right)\left(2-x\right)=0\Leftrightarrow x=-3;x=2\)
4, \(x^3-8+2x^2-4x=0\Leftrightarrow\left(x-2\right)\left(x^2+2x+4\right)+2x\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x+2\right)^2=0\Leftrightarrow x=\pm2\)
5, \(x^2\left(x-3\right)+18-6x=0\Leftrightarrow x^2\left(x-3\right)-6\left(x-3\right)=0\)
\(\Leftrightarrow\left(x^2-6\right)\left(x-3\right)=0\Leftrightarrow x=\pm\sqrt{6};x=3\)
tìm x
3, ( x - 2 ) mũ 2 - 5( 2 - x ) = 0
x=-3, x=2
4, ( x mũ 3 - 8 ) + 2x mũ 2 - 4x = 0
x= 2 , x= -2
5, x mũ 2 ( x - 3 ) + 18 - 6x = 0
x=-căn bậc hai(6), x=căn bậc hai(6), x=3
Trả lời:
j, ( x + 1 )2 - ( 2x - 1 )2 = 0
<=> ( x + 1 - 2x + 1 ) ( x + 1 + 2x - 1 ) = 0
<=> ( 2 - x ) 3x = 0
<=> 2 - x = 0 hoặc 3x = 0
<=> x = 2 hoặc x = 0
Vậy x = 2; x = 0 là nghiệm của pt.
k, Sửa đề: 8x3 + 12x - 1 = 6x2
<=> 8x3 + 12x - 1 - 6x2 = 0
<=> ( 2x )2 - 3.x2.2 + 3.x.22 - 13 = 0
<=> ( 2x - 1 )3 = 0
<=> 2x - 1 = 0
<=> 2x = 1
<=> x = 1/2
Vậy x = 1/2 là nghiệm của pt.
l, x3 + 15x2 + 75x + 125 = 0
<=> x3 + 3.x2.5 + 3.x.52 + 53 = 0
<=> ( x + 5 )3 = 0
<=> x + 5 = 0
<=> x = - 5
Vậy x = - 5 là nghiệm của pt.
a, \(x^3+3x^2-\left(x+3\right)=0\Leftrightarrow x^2\left(x+3\right)-\left(x+3\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x+1\right)\left(x+3\right)=0\Leftrightarrow x=1;x=-1;x=-3\)
b, \(15x-5+6x^2-2x=0\Leftrightarrow5\left(3x-1\right)+2x\left(3x-1\right)=0\)
\(\Leftrightarrow\left(2x+5\right)\left(3x-1\right)=0\Leftrightarrow x=-\frac{5}{2};x=\frac{1}{3}\)
c, \(5x-2-25x^2+10x=0\)
\(\Leftrightarrow\left(5x-2\right)-5x\left(5x-2\right)=0\Leftrightarrow\left(1-5x\right)\left(5x-2\right)=0\Leftrightarrow x=\frac{2}{5};x=\frac{1}{5}\)
b, x = -5/3 hoặc x = 4/3.
c, x = 0 hoặc x = 3, -3.
d, x = 0 hoặc x = 2, -2.
e, x = 1 hoặc x = \(\dfrac{-1}{2}\).
a: \(\Leftrightarrow x^2-40x+400-x^2-4x-3=-7\)
=>-44x+397=-7
=>-44x=-404
hay x=101
b: \(\Leftrightarrow\left[{}\begin{matrix}3x+5=0\\4-3x=0\end{matrix}\right.\Leftrightarrow x\in\left\{-\dfrac{5}{3};\dfrac{4}{3}\right\}\)
c: \(\Leftrightarrow x\left(x^2-9\right)=0\)
=>x(x-3)(x+3)=0
hay \(x\in\left\{0;3;-3\right\}\)
d: \(\Leftrightarrow x\left(x-2\right)\left(x+2\right)=0\)
hay \(x\in\left\{0;2;-2\right\}\)
e: =>(2x+1)(1-x)=0
=>x=-1/2 hoặc x=1
4, \(x^3-8+2x^2-4x=0\Leftrightarrow\left(x-2\right)\left(x^2+2x+4\right)+2x\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x+2\right)^2=0\Leftrightarrow x=\pm2\)
5, \(x^2\left(x-3\right)+18-6x=0\Leftrightarrow x^2\left(x-3\right)-6\left(x-3\right)=0\)
\(\Leftrightarrow\left(x^2-6\right)\left(x-3\right)=0\Leftrightarrow x=\pm\sqrt{6};x=3\)
\(6x^3+x^2-2x=0\)
\(\Leftrightarrow x\left(6x^2+x-2\right)=0\)
\(\Leftrightarrow x\left[2x\left(3x+2\right)-\left(3x+2\right)\right]=0\)
\(\Leftrightarrow x\left(2x-1\right)\left(3x+2\right)=0\Leftrightarrow x=0;\frac{1}{2};-\frac{2}{3}\)