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a/ \(\left(2x\right)^2-2.2x.3+3^2-16=0\)
\(\Leftrightarrow\left(2x-3\right)^2=16\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-3=4\\2x-3=-4\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}2x=7\\2x=-1\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=\dfrac{7}{2}\\x=\dfrac{-1}{2}\end{matrix}\right.\)
b/ \(x^2+2\sqrt{3}.x+\left(\sqrt{3}\right)^2-4=0\)
\(\Leftrightarrow\left(x+\sqrt{3}\right)^2=4\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\sqrt{3}=2\\x+\sqrt{3}=-2\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=2-\sqrt{3}\\x=-2-\sqrt{3}\end{matrix}\right.\)
c/ \(3x^2-6x+3-2=0\)
\(\Leftrightarrow3\left(x^2-2x+1\right)=2\)
\(\Leftrightarrow\left(x-1\right)^2=\dfrac{2}{3}\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=\dfrac{\sqrt{6}}{3}\\x-1=\dfrac{-\sqrt{6}}{3}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=\dfrac{3+\sqrt{6}}{3}\\x=\dfrac{3-\sqrt{6}}{3}\end{matrix}\right.\)
d/ \(\left(\sqrt{2}x\right)^2-2.2.\left(\sqrt{2}x\right)+2^2-2=0\)
\(\Leftrightarrow\left(\sqrt{2}x-2\right)^2=2\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{2}x-2=\sqrt{2}\\\sqrt{2}x-2=-\sqrt{2}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}\sqrt{2}x=2+\sqrt{2}\\\sqrt{2}x=2-\sqrt{2}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=\sqrt{2}+1\\x=\sqrt{2}-1\end{matrix}\right.\)
Hộp thư của chị có vấn đề rồi, không đọc được tin nhắn TvT
a: \(A=\left(\dfrac{6x+4}{\left(\sqrt{3x}-2\right)\left(3x+2\sqrt{3x}+4\right)}-\dfrac{\sqrt{3x}}{3x+2\sqrt{3x}+4}\right)\left(\dfrac{1+\left(\sqrt{3x}\right)^3}{1+\sqrt{3x}}-\sqrt{3x}\right)\)
\(=\dfrac{6x+4-3x+2\sqrt{3x}}{\left(\sqrt{3x}-2\right)\left(3x+2\sqrt{3x}+4\right)}\cdot\left(1-\sqrt{3x}\right)^2\)
\(=\dfrac{\left(\sqrt{3x}-1\right)^2}{\sqrt{3x}-2}\)
b: Để A là số nguyên thì \(3x-2\sqrt{3x}+1⋮\sqrt{3x}-2\)
=>\(\sqrt{3x}-2\in\left\{1;-1;3;-3\right\}\)
=>\(3x\in\left\{9;1;25\right\}\)
hay x=3
Lần sau ghi dấu ra xíu nhé :v
a) Đặt \(\sqrt{x}=a\Rightarrow B=\left(\dfrac{a}{a+4}+\dfrac{4}{a-4}\right):\dfrac{a^2+16}{a+2}\)
Quy đồng,rút gọn : \(B=\dfrac{a+2}{a^2-16}\Rightarrow B=\dfrac{\sqrt{x}+2}{x-16}\)
b) \(B\left(A-1\right)=\dfrac{\sqrt{x}+2}{x-16}\left(\dfrac{\sqrt{x}+4}{\sqrt{x}+2}-1\right)=\dfrac{2}{x-16}\)
x - 16 là ước của 2 => \(x\in\left\{14;15;17;18\right\}\)
mới làm quen toán 9 ;v có gì k rõ ae chỉ bảo nhé :))
Cau 1:
a: \(A=\dfrac{\left(\sqrt{a}-2\right)\left(a+2\sqrt{a}+4\right)+2\sqrt{a}\left(\sqrt{a}-2\right)}{a-4}\)
\(=\dfrac{\left(\sqrt{a}-2\right)\left(a+4\sqrt{a}+4\right)}{a-4}=\dfrac{\left(\sqrt{a}+2\right)^2}{\sqrt{a}+2}=\sqrt{a}+2\)
c: \(=\dfrac{\left|c+1\right|}{\left|c\right|-1}\)
TH1: c>0
\(C=\dfrac{c+1}{c-1}\)
TH2: c<0
\(C=\dfrac{\left|c+1\right|}{-\left(c+1\right)}=\pm1\)
a. A có nghĩa khi \(\left\{{}\begin{matrix}x\ge0\\\sqrt{x}-1\ne\\\frac{x+\sqrt{x}}{\sqrt{x}+1}\ne0\end{matrix}\right.0\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\x\ne1\end{matrix}\right.\)
A\(=\frac{x-\sqrt{x}+\sqrt{x}-1}{\sqrt{x}-1}.\frac{\sqrt{x}+1}{x+\sqrt{x}}\)\(=\frac{x-1}{\sqrt{x}-1}.\frac{\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}+1\right)}=\frac{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}{\sqrt{x}-1}.\frac{\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}+1\right)}=\frac{\sqrt{x}+1}{\sqrt{x}}\)
b. \(x=7+4\sqrt{3}\Rightarrow\)A = \(\frac{\sqrt{7+4\sqrt{3}}+1}{\sqrt{7+4\sqrt{3}}}=\frac{\sqrt{\left(2+\sqrt{3}\right)^2}+1}{\sqrt{\left(2+\sqrt{3}\right)^2}}=\frac{3+\sqrt{3}}{2+\sqrt{3}}\)
b \(P=\dfrac{\sqrt{x}+\sqrt{x}+2}{x-4}\cdot\dfrac{\sqrt{x}-2}{2}=\dfrac{\sqrt{x}+1}{\sqrt{x}+2}\)
a: Khi x=64 thì \(P=\dfrac{8+1}{8+2}=\dfrac{9}{10}\)
a) \(4-2\sqrt{3}=\left(\sqrt{3}+1\right)^2\)
b)\(7+4\sqrt{3}=\left(2+\sqrt{3}\right)^2\)