`a)2-50x^2=0`
`<=>50x^2=2`
`<=>x^2=1/25`
`<=>x=+-1/5`
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`b)x(x-1)=-x+2`
`<=>x^2-x+x=2`
`<=>x^2=2`
`<=>x=+-\sqrt{2}`
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`c)8x^3+12x^2+6x-63=0`
`<=>8x^3-12x^2+24x^2-36x+42x-63=0`
`<=>4x^2(2x-3)+12x(2x-3)+21(2x-3)=0`
`<=>(2x-3)(4x^2+12x+21)=0`
`<=>(2x-3)[(2x+3)^2+12]=0`
Mà `(2x+3)^2+12 > 0`
`=>2x-3=0`
`<=>x=3/2`
a) \(2-50x^2=0\)
\(50x^2=2\)
\(x^2=\dfrac{1}{25}\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{5}\\x=-\dfrac{1}{5}\end{matrix}\right.\)
b) \(x\left(x-1\right)=-x+2\)
\(x^2-x=-x+2\)
\(x^2=2\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{2}\\x=-\sqrt{2}\end{matrix}\right.\)
c) \(8x^3+12x^2+6x-63=0\)
\(\left(8x^3-12x^2\right)+\left(24x^2-36x\right)+\left(42x-63\right)=0\)
\(4x^2\left(2x-3\right)+12x\left(2x-3\right)+21\left(2x-3\right)=0\)
\(\left(2x-3\right)\left(4x^2+12x+21\right)=0\)
Vì \(4x^2+12x+21=\left(2x+3\right)^2+12>0\)
\(2x-3=0\)
\(x=\dfrac{3}{2}\)
