Giai bpt :
\(\sqrt{x^2-4x+3}-\sqrt{2x^2-3x+1}\ge x-1\)
giai bpt
\(\sqrt{x^2-4x+3}-\sqrt{2x^2-3x+1}=x-1\)
ĐKXĐ: ...
\(\Leftrightarrow\sqrt{\left(x-1\right)\left(x-3\right)}-\sqrt{\left(x-1\right)\left(2x-1\right)}-\left(x-1\right)=0\)
- Với \(x=1\) là 1 nghiệm
- Với \(x\le\frac{1}{2}\)
\(\Leftrightarrow\sqrt{3-x}-\sqrt{1-2x}+\sqrt{1-x}=0\)
\(\Leftrightarrow\sqrt{3-x}+\sqrt{1-x}=\sqrt{1-2x}\)
\(\Leftrightarrow4-2x+2\sqrt{x^2-4x+3}=1-2x\)
\(\Leftrightarrow2\sqrt{x^2-4x+3}=-3\left(vn\right)\)
- Với \(x\ge3\)
\(\Leftrightarrow\sqrt{x-3}-\sqrt{2x-1}-\sqrt{x-1}=0\)
\(\Leftrightarrow\sqrt{x-3}=\sqrt{2x-1}+\sqrt{x-1}\)
\(\Leftrightarrow x-3=3x-2+2\sqrt{2x^2-3x+1}\)
\(\Leftrightarrow2\sqrt{2x^2-3x+1}=-2x-1\left(vn\right)\)
Vậy pt có nghiệm duy nhất \(x=1\)
giải bpt
\(\left(\sqrt{x+4}-1\right)\sqrt{x+2}\ge\frac{x^3+4x^2+3x-2\left(x+3\right)\sqrt[3]{2x+3}}{\left(\sqrt[3]{2x+3}-3\right)\left(\sqrt{x+4}+1\right)}\)
giải BPT :
a. \(\sqrt[3]{x+6}+\sqrt{x-1}\ge x^2-1\)
b.2\(\sqrt[3]{x+4}+\sqrt{2x+7}+x^2+8x+13\)
c.\(4x^3+5x^2+1\ge\sqrt{3x+1}-3x\)
giúp với ạ
giải bpt:
1. \(\frac{\sqrt{-3x^2+x+4}+2}{x}< 2\)
2. \(\sqrt{x^2-3x+2}+\sqrt{x^2-4x+3}\ge2\sqrt{x^2-5x+4}\)
3. \(\sqrt{x^2-8x+15}+\sqrt{x^2+2x-15}\le\sqrt{4x^2-18x=18}\)
4. 4(x+1)2 \(\ge\) (2x +10)( 1- \(\sqrt{3+2x}\))2
5. \(\sqrt{1+x}-\sqrt{1-x}\ge x\)
Giai bpt
1) \(\sqrt{x-2x^2+1}>1-x\)
2) \(x^2+\sqrt{2x^2+4x+3}\ge6-2x\)
\(\sqrt{x-2x^2+1}>1-x\)
TH1: \(1-x\ge0\Rightarrow x\le1\)
\(\sqrt{x-2x^2+1}>1-x\\ \Leftrightarrow x-2x^2+1>x^2-2x+1\\ \Leftrightarrow-2x^2>-2x\\ \Leftrightarrow-2x^2+2x>0\\ \Leftrightarrow-2x\left(x-1\right)>0\\ \Leftrightarrow x\left(x-1\right)< 0\\ \Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 0\\x-1>0\end{matrix}\right.\\\left\{{}\begin{matrix}x>0\\x-1< 0\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 0\\x>1\end{matrix}\right.\\\left\{{}\begin{matrix}x>0\\x< 1\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x\in\varnothing\\x\in\left(0;1\right)\end{matrix}\right.\)
TH2: \(1-x< 0\Leftrightarrow x>1\)
Tương tự ........
giải các bpt sau:
\(\sqrt{x+2}+\sqrt{x-1}< \sqrt{3x+3}\)
\(\sqrt{x-3}+\sqrt{2x+1}< \sqrt{5x-4}\)
\(\sqrt{x+2}+\sqrt{2x-1}\ge\sqrt{6x-1}\)
a/ ĐKXĐ \(x\ge1\)
\(\Leftrightarrow2x+1+2\sqrt{x^2+x-2}< 3x+3\)
\(\Leftrightarrow2\sqrt{x^2+x-2}< x+2\)
\(\Leftrightarrow4\left(x^2+x-2\right)< \left(x+2\right)^2\)
\(\Leftrightarrow3x^2< 12\Leftrightarrow x^2< 4\Rightarrow-2< x< 2\)
Vậy nghiệm của BPT là \(1\le x< 2\)
b/ ĐKXĐ: \(x\ge3\)
\(\Leftrightarrow3x-2+2\sqrt{2x^2-5x-3}< 5x-4\)
\(\Leftrightarrow\sqrt{2x^2-5x-3}< x-1\)
\(\Leftrightarrow2x^2-5x-3< x^2-2x+1\)
\(\Leftrightarrow x^2-3x-4< 0\Rightarrow-1< x< 4\)
\(\Rightarrow3\le x< 4\)
c/ ĐKXĐ: \(x\ge\frac{1}{2}\)
\(\Leftrightarrow3x+1+2\sqrt{2x^2+3x-2}\ge6x-1\)
\(\Leftrightarrow2\sqrt{2x^2+3x-2}\ge3x-2\)
- Với \(\frac{1}{2}\le x< \frac{2}{3}\Rightarrow\left\{{}\begin{matrix}VT\ge0\\VP< 0\end{matrix}\right.\) BPT luôn đúng
- Với \(x\ge\frac{2}{3}\) hai vế ko âm
\(\Leftrightarrow4\left(2x^2+3x-2\right)\ge\left(3x-2\right)^2\)
\(\Leftrightarrow x^2-24x+12\le0\) \(\Rightarrow\frac{2}{3}\le x\le12+2\sqrt{33}\)
Nghiệm của BPT là \(\frac{1}{2}\le x\le12+2\sqrt{33}\)
giải bpt sau : \(\sqrt{x^2-3x+20}+\sqrt{x^2-4x+3}\ge\sqrt{x^2-5x+4}\)
giải các BPT :
1. \(\sqrt{x^2-3x+2}+\sqrt{x^2-3x+16}>3\)
2.\(\sqrt{2x^2+8x+6}+\sqrt{x^2-1}\le2x+2\)
3.\(\sqrt{2x-1}+\sqrt{3x-2}< \sqrt{4x-3}+\sqrt{5x-4}\)
1. Đợi chút t tìm cách ngắn gọn.
2. ĐK: \(\left\{{}\begin{matrix}2x^2+8x+6\ge0\\x^2-1\ge0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x\le-3\\x\ge1\\x=-1\end{matrix}\right.\) (*)
BPT\(\Leftrightarrow\left\{{}\begin{matrix}x\ge-1\\3x^2+8x+5+2\sqrt{\left(2x^2+8x+6\right)\left(x^2-1\right)}\le\left(2x+2\right)^2\left(1\right)\end{matrix}\right.\)
Giải (1) \(\Leftrightarrow x^2-1-2\sqrt{\left(2x^2+8x+6\right)\left(x^2-1\right)}\ge0\)
\(\Leftrightarrow\sqrt{x^2-1}\left(\sqrt{x^2-1}-2\sqrt{2x^2+8x+6}\right)\ge0\)
TH1: \(\sqrt{x^2-1}=0\Leftrightarrow x=\pm1\) (tm)
TH2: \(x^2-1\ne0\)
\(\Leftrightarrow\sqrt{x^2-1}-2\sqrt{2x^2+8x+6}\ge0\)
\(\Leftrightarrow\sqrt{x^2-1}\ge2\sqrt{2x^2+8x+6}\)
\(\Leftrightarrow x^2-1\ge8x^2+32x+24\)
\(\Leftrightarrow7x^2+32x+25\le0\)
\(\Leftrightarrow-\frac{25}{7}\le x\le-1\) kết hợp đk (*) và đk để giải bpt
=>\(x=-1\)
Vậy \(x=\pm1\)
3. ĐK: \(x\ge\frac{4}{5}\)
\(BPT\Leftrightarrow\sqrt{5x-4}-\sqrt{3x-2}+\sqrt{4x-3}-\sqrt{2x-1}>0\)
\(\Leftrightarrow\frac{2x-2}{\sqrt{5x-4}+\sqrt{3x-2}}+\frac{2x-2}{\sqrt{4x-3}+\sqrt{2x-1}}>0\)
\(\Leftrightarrow\left(x-1\right)\left(\frac{1}{\sqrt{5x-4}+\sqrt{3x-2}}+\frac{1}{\sqrt{4x-3}+\sqrt{2x-1}}\right)>0\)
\(\Leftrightarrow x-1>0\) \(\Leftrightarrow x>1\)
Vậy \(x>1\)