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Đặt \(a=x^2\)
\(\Rightarrow4a^2-11a+6=0\)
ta có: \(\Delta=11^2-4.4.6=121-96=25>0\)
=> Phương trình có 2 nghiệm phân biệt: \(a1=\frac{-b+\sqrt{\Delta}}{2a}=\frac{11+\sqrt{25}}{2.4}=\frac{16}{8}=2\Leftrightarrow x^2=2\Leftrightarrow x=\pm\sqrt{2}\)
\(a2=\frac{-b-\sqrt{\Delta}}{2a}=\frac{11-\sqrt{25}}{2.4}=\frac{6}{8}=\frac{3}{4}\)\(\Leftrightarrow x^2=\frac{3}{4}\Leftrightarrow x=\pm\sqrt{\frac{3}{4}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
ĐKXĐ: \(x\notin\left\{3;-3\right\}\)
Ta có: \(\dfrac{2x}{x-3}=\dfrac{x^2+11x-6}{x^2-9}\)
\(\Leftrightarrow\dfrac{2x\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}=\dfrac{x^2+11x-6}{\left(x-3\right)\left(x+3\right)}\)
Suy ra: \(2x^2+6x=x^2+11x-6\)
\(\Leftrightarrow2x^2+6x-x^2-11x+6=0\)
\(\Leftrightarrow x^2-5x+6=0\)
\(\Leftrightarrow x^2-2x-3x+6=0\)
\(\Leftrightarrow x\left(x-2\right)-3\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\left(nhận\right)\\x=3\left(loại\right)\end{matrix}\right.\)
Vậy: S={2}
b) Ta có: \(3x^2+\left(1-\sqrt{3}\right)x+\sqrt{3}-4=0\)
\(\Leftrightarrow3x^2-\left(\sqrt{3}-1\right)x+\sqrt{3}-4=0\)
\(\Leftrightarrow3x^2-\left(\sqrt{3}-1\right)x+\sqrt{3}-1-3=0\)
\(\Leftrightarrow\left(3x^2-3\right)-\left(\sqrt{3}-1\right)\left(x-1\right)=0\)
\(\Leftrightarrow3\left(x-1\right)\left(x+1\right)-\left(\sqrt{3}-1\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(3x+3-\sqrt{3}+1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(3x+4-\sqrt{3}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\3x+4-\sqrt{3}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\3x=\sqrt{3}-4\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{\sqrt{3}-4}{3}\end{matrix}\right.\)
Vậy: \(S=\left\{1;\dfrac{\sqrt{3}-4}{3}\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: ĐKXĐ: x>=-2
\(PT\Leftrightarrow3\cdot3\sqrt{x+2}=\dfrac{1}{2}\cdot2\sqrt{x+2}+16\)
=>\(9\sqrt{x+2}-\sqrt{x+2}=16\)
=>\(8\sqrt{x+2}=16\)
=>\(\sqrt{x+2}=2\)
=>x+2=4
=>x=2
b: ĐKXĐ: \(x\in R\)
\(5+\sqrt{x^2-4x+4}=9\)
=>\(\left|x-2\right|=4\)
=>x-2=4 hoặc x-2=-4
=>x=6 hoặc x=-2
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x^2 + x - 2 = 0
<=> ( x^2 - x ) + ( 2x - 2 ) = 0
<=> x . ( x - 1 ) + 2 . ( x - 1 ) = 0
<=> ( x - 1 ) . ( x + 2 ) = 0
<=> x - 1 = 0 hoặc x + 2 = 0
<=> x = 1 hoặc x = -2
Vậy .......
Tk mk nha
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\(x^2-3x+1=0\)
\(a=1,b=-3,c=1\)
\(\Delta=b^2-4ac\)\(=\left(-3\right)^2-4\times1\times1\)\(=5>0\)
\(\Rightarrow pt\)CÓ 2 NO PHÂN BIỆT
\(x_1=\frac{-b-\sqrt{\Delta}}{2a}=\frac{3-\sqrt{5}}{2}\)\(;x_2=\frac{-b+\sqrt{\Delta}}{2a}=\frac{3+\sqrt{5}}{2}\)
VẬY....
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : \(\left(2-m^2\right)m=-1\)
\(\Leftrightarrow2m-m^3+1=0\)
\(\Leftrightarrow m^3-2m-1=0\)
\(\Leftrightarrow m^3+m^2-m^2-m-m-1=0\)
\(\Leftrightarrow m^2\left(m+1\right)-m\left(m+1\right)-\left(m+1\right)=0\)
\(\Leftrightarrow\left(m+1\right)\left(m^2-m-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}m+1=0\\m^2-m-1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}m=-1\\m=\dfrac{1\pm\sqrt{5}}{2}\end{matrix}\right.\)
Vậy ...
\(4x^4-11x^2+6=0\)
\(\Leftrightarrow4x^4-8x^2-3x^2+6=0\)
\(\Leftrightarrow4x^2\left(x^2-2\right)-3\left(x^2-2\right)=0\)
\(\Leftrightarrow\left(x^2-2\right)\left(4x^2-3\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x^2-2=0\\4x^2-3=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\pm\sqrt{2}\\x=\pm\sqrt{\frac{3}{4}}\end{cases}}\)
\(S=\left\{\pm\sqrt{2};\pm\sqrt{\frac{3}{4}}\right\}\)
nếu có sai bn thông cảm nha