Toán Lớp 9: $\text{Tìm x}$
$\dfrac{x-4}{\sqrt{x}+1}$ = $\text{4}$
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 9: $\text{Tìm x}$
$\dfrac{x-4}{\sqrt{x}+1}$ = $\text{4}$
Comments ( 2 )
Dkxd:x \ge 0\\
\dfrac{{x – 4}}{{\sqrt x + 1}} = 4\\
\Leftrightarrow x – 4 = 4\sqrt x + 4\\
\Leftrightarrow x – 4\sqrt x = 8\\
\Leftrightarrow x – 4\sqrt x + 4 = 12\\
\Leftrightarrow {\left( {\sqrt x – 2} \right)^2} = 12\\
\Leftrightarrow \sqrt x – 2 = 2\sqrt 3 \left( {do:\sqrt x – 2 \ge – 2} \right)\\
\Leftrightarrow \sqrt x = 2 + 2\sqrt 3 \\
\Leftrightarrow x = {\left( {2 + 2\sqrt 3 } \right)^2}\\
\Leftrightarrow x = 4 + 2.2.2\sqrt 3 + 12\\
\Leftrightarrow x = 16 + 8\sqrt 3 \\
Vậy\,x = 16 + 8\sqrt 3
\end{array}$