Toán Lớp 9: Cho P = căn x + 2 / căn x + 1
Tìm các giá trị x để P = 4/3
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Toán Lớp 9: Cho P = căn x + 2 / căn x + 1
Tìm các giá trị x để P = 4/3
Comments ( 2 )
DKXD:\,\,\,x \ge 0\\
P = \dfrac{4}{3}\\
\Leftrightarrow \dfrac{{\sqrt x + 2}}{{\sqrt x + 1}} = \dfrac{4}{3}\\
\Leftrightarrow 3.\left( {\sqrt x + 2} \right) = 4.\left( {\sqrt x + 1} \right)\\
\Leftrightarrow 3\sqrt x + 6 = 4\sqrt x + 4\\
\Leftrightarrow 3\sqrt x + 6 – 4\sqrt x – 4 = 0\\
\Leftrightarrow 2 – \sqrt x = 0\\
\Leftrightarrow \sqrt x = 2\\
\Leftrightarrow x = {2^2}\\
\Leftrightarrow x = 4
\end{array}\)