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câu b đk x>= -1/4
\(x+\sqrt{x+\dfrac{1}{2}+\sqrt{x+\dfrac{1}{4}}}=2\)
\(x+\sqrt{\left(\sqrt{x+\dfrac{1}{4}}+\dfrac{1}{2}\right)^2}=2\)
\(\left(\sqrt{x+\dfrac{1}{4}}+\dfrac{1}{2}\right)^2=2\)
\(x+\dfrac{1}{4}=\left(\sqrt{2}-\dfrac{1}{2}\right)^2\)
\(x=\left(\sqrt{2}-\dfrac{1}{2}\right)^2-\dfrac{1}{4}\)
\(x=\left(\sqrt{2}-\dfrac{1}{2}-\dfrac{1}{2}\right)\left(\sqrt{2}-\dfrac{1}{2}+\dfrac{1}{2}\right)\)
\(x=\sqrt{2}\left(\sqrt{2}-1\right)=2-\sqrt{2}\)
Giải phương trình \(\sqrt{x-2+\sqrt{2\cdot x+5}}+\sqrt{x+2+3\cdot\sqrt{2\cdot x-5}}=7\cdot\sqrt{2}\)
a: \(=3xy\cdot\dfrac{\sqrt{2}}{\sqrt{xy}}=3\sqrt{2}\sqrt{xy}\)
b: \(=x\cdot\dfrac{\sqrt{6}}{\sqrt{x}}+\dfrac{\sqrt{6}}{3}\sqrt{x}\)
\(=\sqrt{6}\sqrt{x}+\dfrac{\sqrt{6}}{3}\sqrt{x}=\dfrac{4\sqrt{6}}{3}\cdot\sqrt{x}\)
c: \(=\sqrt{xy}+x\cdot\dfrac{\sqrt{y}}{\sqrt{x}}-y\cdot\dfrac{\sqrt{x}}{\sqrt{y}}\)
\(=\sqrt{xy}+\sqrt{xy}-\sqrt{xy}=\sqrt{xy}\)
\(\sqrt{x-2}+2\sqrt{x-3}+\sqrt{x+6+6\sqrt{x-3}}=4\)
\(\left(\text{Đ}\text{KXĐ}:x\ge3\right)\)
\(\Leftrightarrow\sqrt{x-2}+2\sqrt{x-3}+\sqrt{\left(\sqrt{x-3}+3\right)^2}=4\)
\(\Leftrightarrow\sqrt{x-2}+2\sqrt{x-3}+\sqrt{x-3}+3=4\)
\(\Leftrightarrow\Leftrightarrow\sqrt{x-2}+3\sqrt{x-3}-1=0\)
\(\Leftrightarrow\dfrac{x-2-1}{\sqrt{x-2}+1}+3\sqrt{x-3}=0\)
\(\Leftrightarrow\dfrac{x-3}{\sqrt{x-2}+1}+\dfrac{3\left(x-3\right)}{\sqrt{x-3}}=0\)
\(\Leftrightarrow\left(\dfrac{1}{\sqrt{x-2}+1}+\dfrac{3}{\sqrt{x-3}}\right)\left(x-3\right)=0\)
Pt \(\dfrac{1}{\sqrt{x-2}+1}+\dfrac{3}{\sqrt{x-3}}\) vô no
=> x - 3 = 0
<=> x = 3 (nhận)
Câu 2b đề là tìm x chứ nhỉ???
b) \(\sqrt{x^2-4}+\sqrt{x-2}=0\)
Ta có: \(\left\{{}\begin{matrix}\sqrt{x^2-4}\ge0\\\sqrt{x-2}\ge0\end{matrix}\right.\)
=> Dấu = xảy ra <=> \(\left\{{}\begin{matrix}\sqrt{x^2-4}=0\\\sqrt{x-2}=0\end{matrix}\right.\) <=> \(\left\{{}\begin{matrix}x^2-4=0\\x-2=0\end{matrix}\right.\)
<=> \(\left\{{}\begin{matrix}x=\pm2\\x=2\end{matrix}\right.\) <=> x = 2
Vậy x = 2
bài 2 câu b) đề sai rồi bạn
còn bài 1 câu b) mình cảm thấy sai sai