\(\left(x+1\right)\sqrt{6x^2-6x+25}=23x-13\)
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Điều kiện: 4
\(x\ge\frac{1}{2}\)
Ta có:
\(x\left(\sqrt{2x-1}-3\right)=\frac{2\left(2x^2-7x-15\right)}{x^2-6x+13}\)
\(\Leftrightarrow x.\frac{2\left(x-5\right)}{\sqrt{2x-1}+3}=\frac{2\left(x-5\right)\left(2x+3\right)}{x^2-6x+13}\)
\(\Leftrightarrow2\left(x-5\right)\left(\frac{x}{\sqrt{2x-1}+3}-\frac{2x+3}{x^2-6x+13}\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-5=0\\\frac{x}{\sqrt{2x-1}+3}-\frac{2x+3}{x^2-6x+13}\left(1\right)\end{cases}}\)
\(\left(1\right)\Leftrightarrow\frac{\left(x-3\right)+3}{\sqrt{2x-1}+3}-\frac{\left(2x-1\right)+4}{\left(x-3\right)^2+4}=0\)
Đặt \(\hept{\begin{cases}\left(x-3\right)=a\\\sqrt{2x-1}=b\ge0\end{cases}}\)
\(\Rightarrow\frac{a+3}{b+3}-\frac{b^2+4}{a^2+4}=0\)
Tới đây thì đơn giản rồi nhé
b: Đặt \(x^2+5x+4=a\)
\(\Leftrightarrow a=5\sqrt{a+24}\)
\(\Leftrightarrow a^2=25a+600\)
\(\Leftrightarrow a^2-25a-600=0\)
\(\Leftrightarrow\left(a-40\right)\left(a+15\right)=0\)
\(\Leftrightarrow a=-15\)
hay S=∅
\(\Leftrightarrow4x^4+2x^2+2x\sqrt{6x^2+3}-12=0\)
Đặt \(x\sqrt{6x^2+3}=t\Rightarrow6x^4+3x^2=t^2\)
\(\Rightarrow4x^4+2x^2=\frac{2}{3}t^2\)
Pt trở thành:
\(\frac{2}{3}t^2+2t-12=0\Leftrightarrow t^2+3t-18=0\Rightarrow\left[{}\begin{matrix}t=3\\t=-6\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x\sqrt{6x^2+3}=3\left(x>0\right)\\x\sqrt{6x^2+3}=-6\left(x< 0\right)\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}6x^4+3x^2-9=0\\6x^4+3x^2-36=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x^2=1\\x^2=\frac{-1+\sqrt{97}}{2}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=1\\x=-\sqrt{\frac{-1+\sqrt{97}}{2}}\end{matrix}\right.\)
\(E=\dfrac{\left|x-3\right|}{\left(x-3\right)\left(x+3\right)}\left(x+3\right)^2=\dfrac{\left|x-3\right|\left(x+3\right)}{x-3}\left(x\ne\pm3\right)\)
Với \(x>3\Leftrightarrow E=x+3\)
Với \(x< 3\Leftrightarrow E=-x-3\)
\(F=\dfrac{x+5\sqrt{x}-10\sqrt{x}-5\sqrt{x}+25}{\left(\sqrt{x}-5\right)\left(\sqrt{x}+5\right)}\left(x\ge0;x\ne25\right)\\ F=\dfrac{\left(\sqrt{x}-5\right)^2}{\left(\sqrt{x}-5\right)\left(\sqrt{x}+5\right)}=\dfrac{\sqrt{x}-5}{\sqrt{x}+5}\)