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`sqrt{x-2}-2>=sqrt{2x-5}-sqrt{x+1}`
`đk:x>=5/2`
`bpt<=>\sqrt{x-2}+\sqrt{x+1}>=\sqrt{2x-5}+2`
`<=>x-2+x+1+2\sqrt{(x-2)(x+1)}>=2x-5+4+4\sqrt{2x-5}`
`<=>2x-1+2\sqrt{(x-2)(x+1)}>=2x-1+4\sqrt{2x-5}`
`<=>2\sqrt{(x-2)(x+1)}>=4\sqrt{2x-5}`
`<=>sqrt{x^2-x-2}>=2sqrt{2x-5}`
`<=>x^2-x-2>=4(2x-5)`
`<=>x^2-x-2>=8x-20`
`<=>x^2-9x+18>=0`
`<=>(x-3)(x-6)>=0`
`<=>` \(\left[ \begin{array}{l}x \ge 6\\x \le 3\end{array} \right.\)
Kết hợp đkxđ:
`=>` \(\left[ \begin{array}{l}x \ge 6\\\dfrac52 \le x \le 3\end{array} \right.\)
ĐKXĐ: \(\left\{{}\begin{matrix}x\ge-\dfrac{9}{2}\\x\ne0\end{matrix}\right.\)
\(\Leftrightarrow\dfrac{\left(3+\sqrt{9+2x}\right)^2.2x^2}{\left(3-\sqrt{9+2x}\right)^2\left(3+\sqrt{9+2x}\right)^2}< x+21\)
\(\Leftrightarrow\dfrac{\left(3+\sqrt{9+2x}\right)^2.2x^2}{4x^2}< x+21\)
\(\Leftrightarrow\left(3+\sqrt{9+2x}\right)^2< 2x+42\)
\(\Leftrightarrow x+9+3\sqrt{9+2x}< x+21\)
\(\Leftrightarrow\sqrt{9+2x}< 4\)
\(\Leftrightarrow9+2x< 16\Rightarrow x< \dfrac{7}{2}\)
Vậy \(\left\{{}\begin{matrix}-\dfrac{9}{2}\le x< \dfrac{7}{2}\\x\ne0\end{matrix}\right.\)
ĐKXĐ: \(x\ge-\frac{3}{2}\)
Do \(1+\sqrt{3+2x}>0\) nên BPT tương đương:
\(4\left(x+1\right)^2\left(1+\sqrt{3+2x}\right)^2< \left(2x+1\right)\left(1-\sqrt{3+2x}\right)^2\left(1+\sqrt{3+2x}\right)^2\)
\(\Leftrightarrow4\left(x+1\right)^2\left(1+\sqrt{3+2x}\right)^2< \left(2x+1\right).4\left(x+1\right)^2\)
- Với \(x=-1\) ko phải là nghiệm
- Với \(x\ne-1\)
\(\Leftrightarrow\left(1+\sqrt{3+2x}\right)^2< 2x+1\)
\(\Leftrightarrow4+2x+2\sqrt{3+2x}< 2x+1\)
\(\Leftrightarrow2\sqrt{3+2x}< -3\)
BPT vô nghiệm
\(\sqrt{2x-1}\ge0\)
\(\Rightarrow BPT\ge0\) khi
\(3-2x-x^2\ge0\)
\(\Leftrightarrow x^2+2x-3\le0\)
\(\Leftrightarrow\left(x+1\right)^2-4\le0\)
\(\Leftrightarrow\left(x+1\right)^2\le4\)
\(\Leftrightarrow x+1\le2\)
\(\Rightarrow x\le1\)