\(a,x^3-3x^2+3x+1=0\)(1)
Đặt : \(t=x-1\Rightarrow x=t+1\)
Khi đó : \(\left(1\right)\Leftrightarrow\left(t+1\right)^3-3\left(t+1\right)^2+3\left(t+1\right)+1=0\)
\(\Leftrightarrow t^3+2=0\)
\(\Leftrightarrow t^3=-2\)
\(\Leftrightarrow x=\sqrt[3]{-2}=-1,25992105\)
\(\Rightarrow x=t+1=-0,2599210499\)
\(b,25x^2-3=0\)
\(\Leftrightarrow25\left(x^2-\dfrac{3}{25}\right)=0\)
\(\Leftrightarrow x^2=\dfrac{3}{25}\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{\dfrac{3}{25}}\\x=-\sqrt{\dfrac{3}{25}}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{\sqrt{3}}{5}\\x=-\dfrac{\sqrt{3}}{5}\end{matrix}\right.\)
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