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![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{2002x^4+x^4\sqrt{x^2+2002}+x^2}{2001}=2002\)
\(\frac{x^2\left(x^2+2002\right)+x^4\sqrt{x^2+2002}}{2001}=2002\)
\(x^2\sqrt{x^2+2002}\left(\sqrt{x^2+2002}+x^2\right)=2002.2001\)
đặt x^2+2002=a
a-2002=x^2
pt \(\left(a-2002\right)\sqrt{a}\left(\sqrt{a}+a-2002\right)=2002.2001\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(Pt\Leftrightarrow2002x^4+x^4\sqrt{x^2+2002}+x^2-2002.2001=0\)
\(\Leftrightarrow x^4\left(\sqrt{x^2+2002}+2002\right)+x^2-2002.2001=0\)
\(\Leftrightarrow\dfrac{x^4}{\sqrt{x^2+2002}-2002}\left(x^2+2002-2002^2\right)+\left(x^2-2001.2002\right)=0\)
\(\Leftrightarrow\left(x^2-2001.2002\right)\left(\dfrac{x^4}{\sqrt{x^2+2002}-2002}+1\right)=0\)
Done !
![](https://rs.olm.vn/images/avt/0.png?1311)
sao bạn lại có chữ hiệp sĩ ở bên cạnh tên vậy?
sao vậy bạn
k mk nha
![](https://rs.olm.vn/images/avt/0.png?1311)
Đặt \(\sqrt[3]{3x^2-x+2001}=a;-\sqrt[3]{3x^2-7x+2002}=b;-\sqrt[3]{6x-2003}=c\)
Thì ta có được hệ: \(\hept{\begin{cases}a+b+c=\sqrt[3]{2002}\\a^3+b^3+c^3=2002\end{cases}}\)
\(\Leftrightarrow\left(a+b+c\right)^3=a^3+b^3+c^3\)
\(\Leftrightarrow a^3+b^3+c^3+3\left(a+b\right)\left(b+c\right)\left(c+a\right)=a^3+b^3+c^3\)
\(\Leftrightarrow\left(a+b\right)\left(b+c\right)\left(c+a\right)=0\)
Với a = - b thì
\(\sqrt[3]{3x^2-x+2001}=\sqrt[3]{3x^2-7x+2002}\)
\(\Leftrightarrow3x^2-x+2001=3x^2-7x+2002\)
\(\Leftrightarrow6x=1\)
\(\Leftrightarrow x=\frac{1}{6}\)
Tương tự cho 2 trường hợp còn lại
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
hình như...
b) \(x+y+z+8=2\sqrt{x-3}+4\sqrt{y-3}+6\sqrt{z-3}\)
\(\Leftrightarrow x-3+y-3+z-3+17=2\sqrt{x-3}+4\sqrt{y-3}+6\sqrt{z-3}\)
\(\Leftrightarrow\left(x-3-2\sqrt{x-3}+1\right)+\left(y-3-4\sqrt{y-3}+4\right)+\left(z-3-6\sqrt{z-3}+9\right)+3=0\)
\(\Leftrightarrow\left(\sqrt{x-3}-1\right)^2+\left(\sqrt{y-3}-2\right)^2+\left(\sqrt{z-3}-3\right)^2+3=0\) (vô nghiệm, VT >/3)
Kl: ptvn
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x=\frac{\left(5+\sqrt{2}\right)^2\sqrt{\left(5-\sqrt{2}\right)^2}-\left(5-\sqrt{2}\right)^2\sqrt{\left(5+\sqrt{2}\right)^2}}{\frac{\sqrt{\left(\sqrt{13}-3\right)\left(\sqrt{13}-2\right)}+\sqrt{\left(\sqrt{13}+3\right)\left(\sqrt{13}-2\right)}}{\sqrt{13-4}}}\)
\(=\frac{\left(5+\sqrt{2}\right)\left(5+\sqrt{2}\right)\left(5-\sqrt{2}\right)-\left(5-\sqrt{2}\right)\left(5-\sqrt{2}\right)\left(5+\sqrt{2}\right)}{\frac{\sqrt{19-5\sqrt{13}}+\sqrt{7+\sqrt{13}}}{3}}\)
\(=\frac{69\left(5+\sqrt{2}-5+\sqrt{2}\right)}{\frac{1}{\sqrt{2}}\left(\sqrt{38-10\sqrt{13}}+\sqrt{14+2\sqrt{13}}\right)}=\frac{276}{\sqrt{\left(5-\sqrt{13}\right)^2}+\sqrt{\left(\sqrt{13}+1\right)^2}}\)
\(=\frac{276}{5-\sqrt{13}+\sqrt{13}+1}=46\)
\(\Rightarrow A=...\)
\(\Leftrightarrow\sqrt{x-1}\left(\sqrt{x-2001}+\sqrt{x-2002}-\sqrt{x-2003}\right)=0\)
=>x-1=0
=>x=1