Giai bất phương trình:
\(\left(\dfrac{x+1}{\sqrt{x}+1}+\dfrac{1}{x+\sqrt{x}}-\dfrac{1}{\sqrt{x}}\right):\dfrac{\sqrt{x}}{x+2\sqrt{x}+1}\ge2017+\sqrt{2017}\)
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2 tháng 11 2021
\(P=\dfrac{2+x+\sqrt{x}}{\sqrt{x}\left(\sqrt{x}-1\right)}\cdot\dfrac{\sqrt{x}\left(2-\sqrt{x}\right)}{\sqrt{x}-1}\\ P=\dfrac{\left(2-\sqrt{x}\right)\left(x+\sqrt{x}+2\right)}{\left(\sqrt{x}-1\right)^2}\)
18 tháng 8 2021
a: Ta có: \(A=\dfrac{\sqrt{x}+1}{\sqrt{x}-1}+\dfrac{\sqrt{x}-1}{\sqrt{x}+1}-\dfrac{3\sqrt{x}+1}{x-1}\)
\(=\dfrac{x+2\sqrt{x}+1+x-2\sqrt{x}+1-3\sqrt{x}-1}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\)
\(=\dfrac{2x-3\sqrt{x}+1}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\)
\(=\dfrac{\left(2\sqrt{x}-1\right)\left(\sqrt{x}-1\right)}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{2\sqrt{x}-1}{\sqrt{x}+1}\)
18 tháng 8 2021
b: Ta có: \(\left(\sqrt{x}+1\right)\cdot A=x\)
\(\Leftrightarrow\left(\sqrt{x}+1\right)\cdot\dfrac{2\sqrt{x}-1}{\sqrt{x}+1}=x\)
\(\Leftrightarrow x-2\sqrt{x}+1=0\)
\(\Leftrightarrow x=1\left(loại\right)\)
1 tháng 5 2021
a, ĐKXĐ : \(D=R\)
BPT \(\Leftrightarrow x^2+5x+4< 5\sqrt{x^2+5x+4+24}\)
Đặt \(x^2+5x+4=a\left(a\ge-\dfrac{9}{4}\right)\)
BPTTT : \(5\sqrt{a+24}>a\)
\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}a+24\ge0\\a< 0\end{matrix}\right.\\\left\{{}\begin{matrix}a\ge0\\25\left(a+24\right)>a^2\end{matrix}\right.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}-24\le a< 0\\\left\{{}\begin{matrix}a^2-25a-600< 0\\a\ge0\end{matrix}\right.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}-24\le a< 0\\0\le a< 40\end{matrix}\right.\)
\(\Leftrightarrow-24\le a< 40\)
- Thay lại a vào ta được : \(\left\{{}\begin{matrix}x^2+5x-36< 0\\x^2+5x+28\ge0\end{matrix}\right.\)
\(\Leftrightarrow-9< x< 4\)
Vậy ....
1 tháng 5 2021
b, ĐKXĐ : \(x>0\)
BĐT \(\Leftrightarrow2\left(\sqrt{x}+\dfrac{1}{2\sqrt{x}}\right)< x+\dfrac{1}{4x}+1\)
- Đặt \(\sqrt{x}+\dfrac{1}{2\sqrt{x}}=a\left(a\ge\sqrt{2}\right)\)
\(\Leftrightarrow a^2=x+\dfrac{1}{4x}+1\)
BPTTT : \(2a\le a^2\)
\(\Leftrightarrow\left[{}\begin{matrix}a\le0\\a\ge2\end{matrix}\right.\)
\(\Leftrightarrow a\ge2\)
\(\Leftrightarrow a^2\ge4\)
- Thay a vào lại BPT ta được : \(x+\dfrac{1}{4x}-3\ge0\)
\(\Leftrightarrow4x^2-12x+1\ge0\)
\(\Leftrightarrow x=(0;\dfrac{3-2\sqrt{2}}{2}]\cup[\dfrac{3+2\sqrt{2}}{2};+\infty)\)
Vậy ...
31 tháng 5 2017
ĐKXĐ: \(x\ge0,x\ne1\)
\(A=\left(1+\dfrac{\sqrt{x}}{x+1}\right):\left(\dfrac{1}{\sqrt{x}-1}-\dfrac{2\sqrt{x}}{x\sqrt{x}+\sqrt{x}-x-1}\right)-1\)
= \(\dfrac{x+\sqrt{x}+1}{x+1}:\left(\dfrac{x+1-2\sqrt{x}}{\left(x+1\right)\left(\sqrt{x}-1\right)}\right)-1\)
= \(\dfrac{\left(x+\sqrt{x}+1\right)\left(x+1\right)\left(\sqrt{x}-1\right)}{\left(x+1\right)\left(\sqrt{x}-1\right)^2}-1\)
= \(\dfrac{x+\sqrt{x}+1}{\sqrt{x}-1}-1\)
= \(\dfrac{x+\sqrt{x}+1-\sqrt{x}+1}{\sqrt{x}-1}\)
= \(\dfrac{x+2}{\sqrt{x}-1}\)
\(\left(\dfrac{x+1}{\sqrt{x}+1}+\dfrac{1}{x+\sqrt{x}}-\dfrac{1}{\sqrt{x}}\right):\dfrac{\sqrt{x}}{x+2\sqrt{x}+1}=\left(\dfrac{x\sqrt{x}+\sqrt{x}}{x+\sqrt{x}}+\dfrac{1}{x+\sqrt{x}}-\dfrac{\sqrt{x}+1}{x}\right):\dfrac{\sqrt{x}}{\left(\sqrt{x}+1\right)^2}=\dfrac{x\sqrt{x}+\sqrt{x}}{x+\sqrt{x}}:\dfrac{\sqrt{x}}{\cdot\left(\sqrt{x}+1\right)^2}=\dfrac{\sqrt{x}\left(x+1\right)}{\sqrt{x}\left(\sqrt{x}+1\right)}:\dfrac{\sqrt{x}}{\left(\sqrt{x}+1\right)\left(\sqrt{x+1}\right)}=\dfrac{x+1}{\sqrt{x}+1}:\dfrac{\sqrt{x}}{\left(\sqrt{x}+1\right)\left(\sqrt{x}+1\right)}=\dfrac{\left(x+1\right)\left(\sqrt{x}+1\right)\left(\sqrt{x+1}\right)}{\left(\sqrt{x}+1\right)\sqrt{x}}=\dfrac{\left(x+1\right)\left(\sqrt{x}+1\right)}{\sqrt{x}}=\dfrac{x\sqrt{x}+x+\sqrt{x}+1}{\sqrt{x}}\)
\(=x+\sqrt{x}+1+\dfrac{1}{\sqrt{x}}\ge2017+\sqrt{2017}\Leftrightarrow x+\sqrt{x}+\dfrac{1}{\sqrt{x}}\ge2016+\sqrt{2017}\Leftrightarrow x+\sqrt{x}+\dfrac{1}{\sqrt{x}}-2016-\sqrt{2017}\ge0\)
Bài toán sắp hoàn thành rồi đấy cậu giải tiếp nhé! =))