\(2x-8\sqrt{2x-1}=21\)
\(\Leftrightarrow8\sqrt{2x-1}=2x-21\\ \Leftrightarrow64\left(2x-1\right)=\left(2x-21\right)^2\)
\(\Leftrightarrow128x-64=4x^2-84x+441\\ \Leftrightarrow4x^2-84x+441-128x+64=0\)
\(\Leftrightarrow4x^2-212x+502=0\)
\(\Leftrightarrow2x^2-106x+251\)
\(\Delta'=\left(-53\right)^2-2\cdot251=2809-502=2307\)
Vì \(\Delta'>0\) nên pt có 2 nghiệm phân biệt
\(\Rightarrow x_1=\dfrac{53+\sqrt{2307}}{2}\)
\(x_2=\dfrac{53-\sqrt{2307}}{2}\)
Vậy..............................
Đúng 0
Bình luận (0)
