\(x\left(x-5\right)\left(x+5\right)-\left(x-2\right)\left(x^2+2x+4\right)=3\)
<=> \(x\left(x^2-25\right)-\left(x^3+2x^2+4x-2x^2-4x-8\right)=3\)
<=> \(x^3-25x-x^3-2x^2-4x+2x^2+4x+8=3\)
<=> \(-25x+8=3\)
<=> \(-25x=-5\)
<=> \(x=\frac{1}{5}\)
\(25x^2-2=0\)
<=> \(\left(5x\right)^2=2\)
<=> \(\hept{\begin{cases}5x=\sqrt{2}\\5x=-\sqrt{2}\end{cases}}\)
<=> \(\hept{\begin{cases}x=\frac{\sqrt{2}}{5}\\x=\frac{-\sqrt{2}}{5}\end{cases}}\)
\(\left(x+2\right)^2=\left(2x-1\right)^2\)
<=> \(\hept{\begin{cases}x+2=2x-1\\x+2=-2x+1\end{cases}}\)
<=> \(\hept{\begin{cases}-x=-3\\3x=-1\end{cases}}\)
<=> \(\hept{\begin{cases}x=3\\x=\frac{-1}{3}\end{cases}}\)
\(\left(x+2\right)^2-x^2+4=0\)
<=> \(\left(x+2\right)^2-\left(x^2-4\right)=0\)
<=> \(\left(x+2\right)^2-\left(x-2\right)\left(x+2\right)=0\)
<=> \(\left(x+2\right)\left(x+2-x+2\right)=0\)
<=> \(\left(x+2\right).4=0\)
<=> \(x+2=0\)
<=> \(x=-2\)
câu còn lại tương tự nha