giải các phương trình sau
1) 15.\(\sqrt{x^3-1}\)=4x2+8
2) \(\sqrt{2x-3}\)+6=2x+\(\sqrt{x}\)
3) \(\sqrt{x-\frac{1}{x}}\)+\(\frac{4}{x}\)=x+\(\sqrt{2x-\frac{5}{x}}\)
4)\(\sqrt{5x-1}\)-\(\sqrt{x+2}\)=\(\frac{4x-3}{5}\)
5) \(\sqrt{2x-\frac{3}{x}}\)-1=\(\frac{3}{2x}\)-\(\sqrt{\frac{6}{x}-2x}\)
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giải các phương trình sau
1) 15.\(\sqrt{x^3-1}\)=4x2+8
2) \(\sqrt{2x-3}\)+6=2x+\(\sqrt{x}\)
3) \(\sqrt{x-\frac{1}{x}}\)+\(\frac{4}{x}\)=x+\(\sqrt{2x-\frac{5}{x}}\)
4)\(\sqrt{5x-1}\)-\(\sqrt{x+2}\)=\(\frac{4x-3}{5}\)
5) \(\sqrt{2x-\frac{3}{x}}\)-1=\(\frac{3}{2x}\)-\(\sqrt{\frac{6}{x}-2x}\)
5/
Đặt \(\left\{{}\begin{matrix}\sqrt{2x-\frac{3}{x}}=a\ge0\\\sqrt{\frac{6}{x}-2x}=b\ge0\end{matrix}\right.\) \(\Rightarrow a^2+b^2=\frac{3}{x}\)
Pt trở thành:
\(a-1=\frac{a^2+b^2}{2}-b\)
\(\Leftrightarrow a^2+b^2-2a-2b+2=0\)
\(\Leftrightarrow\left(a^2-2a+1\right)+\left(b^2-2b+1\right)=0\)
\(\Leftrightarrow\left(a-1\right)^2+\left(b-1\right)^2=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}a=1\\b=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}\sqrt{2x-\frac{3}{x}}=1\\\sqrt{\frac{6}{x}-2x}=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x^2-x-3=0\\2x^2+x-6=0\end{matrix}\right.\) \(\Rightarrow x=\frac{3}{2}\)
4/
ĐKXĐ: \(x\ge\frac{1}{5}\)
\(\Leftrightarrow\frac{4x-3}{\sqrt{5x-1}+\sqrt{x+2}}=\frac{4x-3}{5}\)
\(\Leftrightarrow\left[{}\begin{matrix}4x-3=0\Rightarrow x=\frac{3}{4}\\\sqrt{5x-1}+\sqrt{x+2}=5\left(1\right)\end{matrix}\right.\)
\(\left(1\right)\Leftrightarrow\sqrt{5x-1}-3+\sqrt{x+2}-2=0\)
\(\Leftrightarrow\frac{5\left(x-2\right)}{\sqrt{5x-1}+3}+\frac{x-2}{\sqrt{x+2}+2}=0\)
\(\Leftrightarrow\left(x-2\right)\left(\frac{5}{\sqrt{5x-1}+3}+\frac{1}{\sqrt{x+2}+2}\right)=0\)
\(\Leftrightarrow x=2\)