Giải bpt: \(\dfrac{\left(3-2x-x^2\right)\sqrt{2x-1}}{\sqrt{2x-1}}\)≥0
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a,ĐK: x\(\ge\)1
⇔\(\sqrt{x-1-2\sqrt{x-1}+1}\)=\(\sqrt{2}\)
⇔\(\sqrt{\left(\sqrt{x-1}-1\right)^2}\)=\(\sqrt{2}\)
⇔\(\left|\sqrt{x-1}-1\right|\)=\(\sqrt{2}\)
TH1:\(\sqrt{x-1}\)-1≥0⇒\(\left|\sqrt{x-1}-1\right|\)=\(\sqrt{x-1}\)-1 bn tự giải ra nha
TH2:\(\sqrt{x-1}\)-1<0⇒\(\left|\sqrt{x-1}-1\right|\)=1-\(\sqrt{x-1}\) bn tự lm nha
c: ĐKXĐ: x>=1/2
Ta có: \(\sqrt{x+\sqrt{2x-1}}+\sqrt{x-\sqrt{2x-1}}=\sqrt2\)
=>\(\sqrt{2x+2\sqrt{2x-1}}+\sqrt{2x-2\sqrt{2x-1}}=2\)
=>\(\sqrt{2x-1+2\cdot\sqrt{2x-1}\cdot1+1}+\sqrt{2x-1-2\sqrt{2x-1}+1}=2\)
=>\(\sqrt{\left(\sqrt{2x-1}+1\right)^2}+\sqrt{\left(\sqrt{2x-1}-1\right)^2}=2\)
=>\(\sqrt{2x-1}+1+\left|\sqrt{2x-1}-1\right|=2\)
=>\(\left|\sqrt{2x-1}-1\right|=2-\sqrt{2x-1}-1=-\sqrt{2x-1}+1=-\left(\sqrt{2x-1}-1\right)\)
=>\(\sqrt{2x-1}-1\le0\)
=>\(\sqrt{2x-1}\le1\)
=>2x-1<=1
=>2x<=2
=>x<=1
=>1/2<=x<=1
d:
ĐKXĐ: x>=-1/4
\(x+\sqrt{x+\frac12+\sqrt{x+\frac14}}=4\)
=>\(x+\sqrt{x+\frac14+2\cdot\sqrt{x+\frac14}\cdot\frac12+\frac14}=4\)
=>\(x+\sqrt{\left(\sqrt{x+\frac14}+\frac12\right)^2}=4\)
=>\(x+\sqrt{x+\frac14}+\frac12=4\)
=>\(x+\frac12+\sqrt{x+\frac14}=4\)
=>\(x+\frac14+2\cdot\sqrt{x+\frac14}\cdot\frac12+\frac14=4\)
=>\(\left(\sqrt{x+\frac14}+\frac12\right)^2=4\)
=>\(\sqrt{x+\frac14}+\frac12=2\)
=>\(\sqrt{x+\frac14}=2-\frac12=\frac32\)
=>\(x+\frac14=\frac94\)
=>x=2(nhận)
`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 \(\left\{{}\begin{matrix}-\dfrac{9}{2}\le x< \dfrac{7}{2}\\x\ne0\end{matrix}\right.\)
5: ĐKXĐ: \(\frac{x+3}{x-7}>0\)
=>x>7 hoặc x<-3
Ta có: \(\left(x-7\right)\cdot\sqrt{\frac{x+3}{x-7}}=x+4\)
=>\(\sqrt{\left(x+3\right)\left(x-7\right)}=x+4\)
=>\(\begin{cases}x+4\ge0\\ \left(x+3\right)\left(x-7\right)=\left(x+4\right)^2\end{cases}\Rightarrow\begin{cases}x\ge-4\\ x^2-4x-21=x^2+8x+16\end{cases}\)
=>\(\begin{cases}x\ge-4\\ -12x=37\end{cases}\Rightarrow x=-\frac{37}{12}\) (nhận)
6: ĐKXĐ: x>=4
Ta có: \(2\sqrt{x-4}+\sqrt{x-1}=\sqrt{2x-3}+\sqrt{4x-16}\)
=>\(2\sqrt{x-4}+\sqrt{x-1}=\sqrt{2x-3}+2\sqrt{x-4}\)
=>\(\sqrt{2x-3}=\sqrt{x-1}\)
=>2x-3=x-1
=>2x-x=-1+3
=>x=2(loại)
7: ĐKXĐ: x>=1
Ta có: \(\sqrt{x+2\sqrt{x-1}}+\sqrt{x-2\sqrt{x-1}}=\frac{x+3}{2}\)
=>\(\sqrt{x-1+2\cdot\sqrt{x-1}+1}+\sqrt{x-1-2\cdot\sqrt{x-1}\cdot1+1}=\frac{x+3}{2}\)
=>\(\sqrt{\left(\sqrt{x-1}+1\right)^2}+\sqrt{\left(\sqrt{x-1}-1\right)^2}=\frac{x+3}{2}\)
=>\(\sqrt{x-1}+1+\left|\sqrt{x-1}-1\right|=\frac{x+3}{2}\) (1)
TH1: \(\sqrt{x-1}-1\ge0\)
=>\(\sqrt{x-1}\ge1\)
=>x-1>=1
=>x>=2
(1) sẽ trở thành: \(\sqrt{x-1}+1+\sqrt{x-1}-1=\frac{x+3}{2}\)
=>\(2\sqrt{x-1}=\frac{x+3}{2}\)
=>\(4\sqrt{x-1}=x+3\)
=>\(16\left(x-1\right)=\left(x+3\right)^2\)
=>\(x^2+6x+9=16x-16\)
=>\(x^2-10x+25=0\)
=>\(\left(x-5\right)^2=0\)
=>x-5=0
=>x=5(nhận)
TH2: \(\sqrt{x-1}-1<0\)
=>\(\sqrt{x-1}<1\)
=>0<=x-1<1
=>1<=x<2
(1) sẽ trở thành: \(\sqrt{x-1}+1+1-\sqrt{x-1}=\frac{x+3}{2}\)
=>\(\frac{x+3}{2}=2\)
=>x+3=4
=>x=1(nhận)
a: \(2\cdot sin\left(x+\dfrac{\Omega}{5}\right)+\sqrt{3}=0\)
=>\(2\cdot sin\left(x+\dfrac{\Omega}{5}\right)=-\sqrt{3}\)
=>\(sin\left(x+\dfrac{\Omega}{5}\right)=-\dfrac{\sqrt{3}}{2}\)
=>\(\left[{}\begin{matrix}x+\dfrac{\Omega}{5}=-\dfrac{\Omega}{3}+k2\Omega\\x+\dfrac{\Omega}{5}=\dfrac{4}{3}\Omega+k2\Omega\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=-\dfrac{8}{15}\Omega+k2\Omega\\x=\dfrac{4}{3}\Omega-\dfrac{\Omega}{5}+k2\Omega=\dfrac{17}{15}\Omega+k2\Omega\end{matrix}\right.\)
b: \(sin\left(2x-50^0\right)=\dfrac{\sqrt{3}}{2}\)
=>\(\left[{}\begin{matrix}2x-50^0=60^0+k\cdot360^0\\2x-50^0=300^0+k\cdot360^0\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}2x=110^0+k\cdot360^0\\2x=350^0+k\cdot360^0\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=55^0+k\cdot180^0\\x=175^0+k\cdot180^0\end{matrix}\right.\)
c: \(\sqrt{3}\cdot tan\left(2x-\dfrac{\Omega}{3}\right)-1=0\)
=>\(\sqrt{3}\cdot tan\left(2x-\dfrac{\Omega}{3}\right)=1\)
=>\(tan\left(2x-\dfrac{\Omega}{3}\right)=\dfrac{1}{\sqrt{3}}\)
=>\(2x-\dfrac{\Omega}{3}=\dfrac{\Omega}{6}+k2\Omega\)
=>\(2x=\dfrac{1}{2}\Omega+k2\Omega\)
=>\(x=\dfrac{1}{4}\Omega+k\Omega\)
\(\sqrt{2x-1}\ge0\)
\(\Rightarrow BPT\ge0\) khi
\(3-2x-x^2\ge0\)
\(\Leftrightarrow x^2+2x-3\le0\)
\(\Leftrightarrow\left(x+1\right)^2-4\le0\)
\(\Leftrightarrow\left(x+1\right)^2\le4\)
\(\Leftrightarrow x+1\le2\)
\(\Rightarrow x\le1\)