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24 tháng 7 2017

a) \(\sqrt{9-12x+4x^2}=4+x\Leftrightarrow\sqrt{\left(3-2x\right)^2}=4+x\)

\(\Leftrightarrow\left|3-2x\right|=4+x\)

th1: \(3-2x\ge0\Leftrightarrow2x\le3\Leftrightarrow\Leftrightarrow x\le\dfrac{3}{2}\)

\(\Rightarrow\left|3-2x\right|=4+x\Leftrightarrow3-2x=4+x\Leftrightarrow3x=-1\Leftrightarrow x=\dfrac{-1}{3}\left(tmđk\right)\)

th2: \(3-2x< 0\Leftrightarrow2x>3\Leftrightarrow x>\dfrac{3}{2}\)

\(\Rightarrow\left|3-2x\right|=4+x\Leftrightarrow2x-3=4+x\Leftrightarrow x=7\left(tmđk\right)\)

vậy \(x=\dfrac{-1}{3};x=7\)

b) \(\sqrt{4-4x+x^2}=\left(x-1\right)^2+x-6\)

\(\Leftrightarrow\sqrt{\left(2-x\right)^2}=x^2-2x+1+x-6\)

\(\Leftrightarrow\left|2-x\right|=x^2-x-5\)

th1: \(2-x\ge0\Leftrightarrow x\le2\)

\(\Rightarrow\left|2-x\right|=x^2-x-5\Leftrightarrow2-x=x^2-x-5\)

\(\Leftrightarrow x^2=7\Leftrightarrow\left\{{}\begin{matrix}x=\sqrt{7}\left(loại\right)\\x=-\sqrt{7}\left(tmđk\right)\end{matrix}\right.\)

th2: \(2-x< 0\Leftrightarrow x>2\)

\(\Rightarrow\left|2-x\right|=x^2-x-5\Leftrightarrow x-2=x^2-x-5\)

\(\Leftrightarrow x^2-2x-3=0\Leftrightarrow x^2+x-3x-3=0\)

\(\Leftrightarrow x\left(x+1\right)-3\left(x+1\right)=0\Leftrightarrow\left(x-3\right)\left(x+1\right)=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-3=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=3\left(tmđk\right)\\x=-1\left(loại\right)\end{matrix}\right.\)

vậy \(x=-\sqrt{7};x=3\)

24 tháng 7 2017

a) \(\sqrt{9-12x+4x^2}=4+x\)

\(\Leftrightarrow\sqrt{\left(3-2x\right)^2}=4+x\)

\(\Leftrightarrow\left|3-2x\right|=4+x\)

\(\Leftrightarrow\left[{}\begin{matrix}3-2x=4+x\\3-2x=-4-x\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}3x=-1\\x=7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{3}\\x=7\end{matrix}\right.\)

Vậy \(x_1=-\dfrac{1}{3};x_2=7\).

b) \(\sqrt{4-4x+x^2}=\left(x-1\right)^2+x-6\)

\(\Leftrightarrow\sqrt{\left(2-x\right)^2}=x^2-2x+1+x-6\)

\(\Leftrightarrow\left|2-x\right|=x^2-x-5\)

\(\Leftrightarrow\left[{}\begin{matrix}2-x=x^2-x-5\\2-x=-x^2+x+5\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2=7\\x^2=2x+3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{7}\left(l\right)\\x=-\sqrt{7}\\x=3\\x=-1\left(l\right)\end{matrix}\right.\)

Vậy \(x_1=-\sqrt{7};x_2=3\).

24 tháng 7 2017

a,  \(\Leftrightarrow\sqrt{\left(3-2x\right)^2=4+x}\)

\(\Leftrightarrow\left|3-2x\right|=4+x\)

\(\Leftrightarrow\orbr{\begin{cases}3-2x=4+x\\3-2x=-4-x\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}3x=-1\\x=7\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{-1}{3}\\x=7\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}\orbr{\begin{cases}x=\sqrt{7}\\x=-\sqrt{7}\end{cases}}\\\left(x-3\right)\left(x-1\right)=0\end{cases}}\)

21 tháng 5 2023

a) `sqrt(x^2-6x _9) = 4-x`

`<=> sqrt[(x-3)^2] =4-x`

`<=> |x-3| =4-x ( đk :x<=4)`

`<=> |x-3| = |4-x|`

`<=> [(x-3 =4-x),(x-3 = x-4):}`

`<=>[(x = 7/2(t//m)),(0=-1(vl)):}`

Vậy `S = {7/2}`

b) `sqrt(x^2 -9) + sqrt(x^2 -6x +9) =0(đk : x>=3(hoặc) x<=-3)`

`<=>sqrt(x^2 -9) =- sqrt(x^2 -6x +9) `

`<=>(sqrt(x^2 -9))^2 =(- sqrt(x^2 -6x +9))^2`

`<=> x^2 -9 = x^2 -6x +9`

`<=> 6x = 9+9 =18`

`<=> x=3(t//m)`

Vậy `S={3}`

 

21 tháng 5 2023

c) `sqrt(x^2 -2x+1) + sqrt(x^2-4x+4) =3`

`<=> sqrt[(x-1)^2] +sqrt[(x-2)^2] =3`

`<=> |x-1| +|x-2| =3`

xét `x<1 =>{(|x-1| =1-x ),(|x-2|=2-x):}`

`=> 1-x +2-x =3`

`=> x = 0(t//m)`

xét `1<=x<2 => {(|x-1|=x-1),(|x-2|= 2-x):}`

`=> x-1 +2-x =3`

`=>1=3 (vl)`

xét `x>=2 => {(|x-1| =x-1),(|x-2|=x-2):}`

`=> x-1+x-2 =3`

`=> x=3(t//m)`

Vậy `S = {0;3}`

31 tháng 10 2021

a, ĐKXĐ: \(x\le2\)

\(\sqrt{4-2x}=5\\ \Leftrightarrow4-2x=25\\ \Leftrightarrow2x=-21\\ \Leftrightarrow x=-10,5\left(tm\right)\)

b, ĐKXĐ: \(x\ge-1\)

\(\sqrt{25\left(x+1\right)}+\sqrt{9x+9}=16\\ \Leftrightarrow5\sqrt{x+1}+\sqrt{9\left(x+1\right)}=16\\ \Leftrightarrow5\sqrt{x+1}+3\sqrt{x+1}=16\\ \Leftrightarrow8\sqrt{x+1}=16\\ \Leftrightarrow\sqrt{x+1}=2\\ \Leftrightarrow x+1=4\\ \Leftrightarrow x=3\)

c, \(\sqrt{4x^2+12x+9}=4\Leftrightarrow4x^2+12x+9=16\\ \Leftrightarrow4x^2+12x-7=0\\ \Leftrightarrow\left(4x^2-2x\right)+\left(14x-7\right)=0\\ \Leftrightarrow2x\left(2x-1\right)+7\left(2x-1\right)=0\\ \Leftrightarrow\left(2x-1\right)\left(2x+7\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-\dfrac{7}{2}\end{matrix}\right.\)

 

31 tháng 10 2021

a: \(\Leftrightarrow4-2x=25\)

hay \(x=-\dfrac{21}{2}\)

c: \(\Leftrightarrow\left|2x+3\right|=4\)

\(\Leftrightarrow\left[{}\begin{matrix}2x+3=4\\2x+3=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-\dfrac{7}{2}\end{matrix}\right.\)

AH
Akai Haruma
Giáo viên
24 tháng 8 2021

a. ĐKXĐ: $x\geq 2$ hoặc $x=1$

PT $\Leftrightarrow \sqrt{(x-1)(x-2)}=\sqrt{x-1}$

$\Leftrightarrow \sqrt{x-1}(\sqrt{x-2}-1)=0$

\(\Leftrightarrow \left[\begin{matrix} \sqrt{x-1}=0\\ \sqrt{x-2}-1=0\end{matrix}\right.\Leftrightarrow \left[\begin{matrix} x=1\\ x=3\end{matrix}\right.\) (đều thỏa mãn)

b.

PT $\Leftrightarrow \sqrt{(x-2)^2}=\sqrt{(2x-3)^2}$

$\Leftrightarrow |x-2|=|2x-3|$

\(\Leftrightarrow \left[\begin{matrix} x-2=2x-3\\ x-2=3-2x\end{matrix}\right.\Leftrightarrow \left[\begin{matrix} x=1\\ x=\frac{5}{3}\end{matrix}\right.\)

AH
Akai Haruma
Giáo viên
24 tháng 8 2021

c. ĐKXĐ: $x=2$ hoặc $x\geq 3$

PT $\Leftrightarrow \sqrt{(x-2)(x-3)}=\sqrt{x-2}$

$\Leftrightarrow \sqrt{x-2}(\sqrt{x-3}-1)=0$

\(\Leftrightarrow \left[\begin{matrix} \sqrt{x-2}=0\\ \sqrt{x-3}-1=0\end{matrix}\right.\Leftrightarrow \left[\begin{matrix} x=2\\ x=4\end{matrix}\right.\) (đều tm)

d.

PT $\Leftrightarrow \sqrt{(2x-1)^2}=\sqrt{(x-3)^2}$

$\Leftrightarrow |2x-1|=|x-3|$

\(\Leftrightarrow \left[\begin{matrix} 2x-1=x-3\\ 2x-1=3-x\end{matrix}\right.\Leftrightarrow \left[\begin{matrix} x=-2\\ x=\frac{4}{3}\end{matrix}\right.\)

3: Ta có: \(\sqrt{4x+1}=x+1\)

\(\Leftrightarrow x^2+2x+1=4x+1\)

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

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

4: Ta có: \(2\sqrt{x-1}+\dfrac{1}{3}\sqrt{9x-9}=15\)

\(\Leftrightarrow3\sqrt{x-1}=15\)

\(\Leftrightarrow x-1=25\)

hay x=26

5: Ta có: \(\sqrt{4x^2-12x+9}=7\)

\(\Leftrightarrow\left|2x-3\right|=7\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=7\\2x-3=-7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=10\\2x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-2\end{matrix}\right.\)

c: Ta có: \(\sqrt{x^2}=x\)

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

hay \(x\ge0\)

d: Ta có: \(\sqrt{x^2-2x+1}=x-1\)

\(\Leftrightarrow\left|x-1\right|=x-1\)

hay \(x\ge1\)

16 tháng 9 2021

a) ĐKXĐ: x <= 2/3

Pt --> 2 - 3x = 4

<=> 3x = -2

<=> x = -2/3 (thỏa)

16 tháng 9 2021

b) ĐKXĐ: x >= 2

Pt --> x^2 + 4x + 4 = x^2 - 4x + 4

<=> 8x = 0<=> x = 0(loại)