a) \(\sqrt{4x-12}+\sqrt{x-3}-\dfrac{1}{3}\sqrt{9x-27}=8\)(*)

Đk: \(x\ge3\)

(*)\(\Rightarrow2\sqrt{x-3}+\sqrt{x-3}-\sqrt{x-3}=8\)

\(\Leftrightarrow\sqrt{x-3}=4\)

\(\Leftrightarrow x=19\)( nhận)

Vậy S=\(\left\{19\right\}\)

b)\(\sqrt{x^2-2x+4}=2x-2\)    Đk \(x^2-2x+4=\left(x-1\right)^2+3>0\forall x\in R\)

\(\Leftrightarrow x^2-2x+4=4x^2-8x+4\)

\(\Leftrightarrow3x^2-6x=0\)

\(\Leftrightarrow3x\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\left(loại\right)\\x=2\left(nhận\right)\end{matrix}\right.\)

Vậy S=\(\left\{2\right\}\)

c)\(\sqrt{x^2-10x+25}-5=3x\)   ĐK \(x^2-10x+25=\left(x-5\right)^2>0\forall x\in R\)

\(\Leftrightarrow\sqrt{\left(x-5\right)^2}=3x-5\)

\(\Leftrightarrow\left|x-5\right|=3x-5\)

\(\Leftrightarrow\left[{}\begin{matrix}x-5=3x-5\\x-5=5-3x\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\left(loại\right)\\x=\dfrac{10}{4}=\dfrac{5}{2}\left(nhận\right)\end{matrix}\right.\)

Vậy S=\(\left\{\dfrac{5}{2}\right\}\)

\(a.-3x^2+15x=0\)

\(\Leftrightarrow3x\left(-x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x=0\\-x+5=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=5\end{matrix}\right.\)

\(b.2x^2-32=0\)

\(\Leftrightarrow2x^2=32\)

\(\Leftrightarrow x^2=16\)

\(\Leftrightarrow\left|x\right|=4\)

\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)

\(c.2x^2-5x+1=0\)

\(a=2;b=-5;c=1\)

\(\Delta=\left(-5\right)^2-4.2.1=17>0\)

Do \(\Delta>0\) nên phương trình có 2 nghiệm phân biệt:

\(x_1=\dfrac{5+\sqrt{17}}{4}\)

\(x_2=\dfrac{5-\sqrt{17}}{4}\)

\(a,-3x^2+15x=0\\ -3x\left(x-5\right)=0\\ \Rightarrow\left\{{}\begin{matrix}x=0\\x-5=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\\x=5\end{matrix}\right.\) 

\(b,\\ 2\left(x^2-16\right)=0\\ \Leftrightarrow x^2-16=0\\ \Leftrightarrow\left(x-4\right)\left(x+4\right)=0\\ \Rightarrow\left\{{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\) 

\(c,\\ \Delta=5^2-4.2=17\\ \Rightarrow x_1,x_2=\dfrac{\Delta\pm b}{2ac}\\ =\dfrac{5\pm\sqrt{17}}{4}\)

you hỏi gì mà ILOVEYOU vậy

là love nha

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My zodiac sign is scorpio.

What grade are you in ?

 I'm in 9 grade.

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No, I'm not.

What is your zodiac sign ? 

my zodiac sign is scorpio

what grade are you in ?

 I'm in 9 grade

are you bored?

no, I'm not

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no no no

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