Pt tương đương:2015x-2014-2\(\sqrt{2017x-2016}\)=-X^2<=>2017x-2016-2\(\sqrt{2017x-2016}\)+1-2x+2-1=-X^2

<=>2017x-2016-2\(\sqrt{2017x-2016}\)+1=-x^2+2x-1

<=>(\(\sqrt{2017x-2016}\)-1)^2=-(x-1)^2

Rồi đánh giá(\(\sqrt{2017x-2016}\)-1)^2>=0

-(x-1)^2=<0 ( Ta thấy chỉ xảy ra khi bằng 0)

=>x-1=0<=>x=1

ĐKXĐ: \(x\ge\frac{2016}{2017}\)

\(x^2+2015x-2014=2\sqrt{2017x-2016}\)

\(\Leftrightarrow x^2+2017x-2x-2016+1+1=2\sqrt{2017x-2016}\)

\(\Leftrightarrow\left(x^2-2x+1\right)+\left[\left(2017x-2016\right)-2\sqrt{2017x-2016}+1\right]=0\)

\(\Leftrightarrow\left(x-1\right)^2+\left(\sqrt{2017x-2016}-1\right)^2=0\)

\(\Leftrightarrow\orbr{\begin{cases}\left(x-1\right)^2=0\\\left(\sqrt{2017x-2016}-1\right)^2=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x-1=0\\\sqrt{2017x-2016}-1=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=1\\\sqrt{2017x-2016}=1\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=1\\2017x-2016=1\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=1\\2017x=2017\end{cases}\Leftrightarrow\orbr{\begin{cases}x=1\\x=1\end{cases}}}\)

Hay : x = 1 (tm ĐKXĐ)

=.= hok tốt!!

a/ Với \(x=2016\Rightarrow2017=x+1\)

\(A=x^6-\left(x+1\right)x^5+\left(x+1\right)x^4-\left(x+1\right)x^3+\left(x+1\right)x^2-\left(x+1\right)x+2025\)

\(A=x^6-x^6-x^5+x^5+x^4-x^4-x^3+x^3+x^2-x^2-x+2025\)

\(A=2025-x=9\)

b/ Với \(x=-1\Rightarrow\left\{{}\begin{matrix}x^{2k}=1\\x^{2k+1}=-1\end{matrix}\right.\) ta có:

\(Q=2017-2016+2015-2014+...+3-2+1\)

\(Q=1+1+1+...+1+1\) (có \(\frac{2016}{2}+1=1009\) số 1)

\(Q=1009\)

\(DK:x\ge\frac{2018}{2019}\)

\(PT\Leftrightarrow x^2-2x+1+2019x-2018-2\sqrt{2019x-2018}+1=0\)

\(\Leftrightarrow\left(x-1\right)^2+\left(\sqrt{2019x-2018}-1\right)^2=0\)

\(\Leftrightarrow\hept{\begin{cases}\left(x-1\right)^2=0\\\left(\sqrt{2019x-2018}-1\right)^2=0\end{cases}}\Leftrightarrow x=1\left(TM\right)\)

ĐKXĐ: \(x\notin\left\{-\dfrac{1}{2014};-\dfrac{2}{2015};-\dfrac{3}{2016};-\dfrac{4}{2017}\right\}\)

Ta có: \(\dfrac{1}{2014x+1}-\dfrac{1}{2015x+2}=\dfrac{1}{2016x+3}-\dfrac{1}{2017x+4}\)

\(\Leftrightarrow\dfrac{2015x+2-2014x-1}{\left(2014x+1\right)\left(2015x+2\right)}=\dfrac{2017x+4-2016x-3}{\left(2016x+3\right)\left(2017x+4\right)}\)

\(\Leftrightarrow\dfrac{x+1}{\left(2014x+1\right)\left(2015x+2\right)}-\dfrac{x+1}{\left(2016x+3\right)\left(2017x+4\right)}=0\)

\(\Leftrightarrow\left(x+1\right)\left(\dfrac{1}{\left(2014x+1\right)\left(2015x+2\right)}-\dfrac{1}{\left(2016x+3\right)\left(2017x+4\right)}\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\\dfrac{1}{\left(2014x+1\right)\left(2015x+2\right)}=\dfrac{1}{\left(2016x+3\right)\left(2017x+4\right)}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\4058210x^2+6043x+2=4066272x^2+14115x+12\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\8062x^2+8072x+10=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\8062x^2+8062x+10x+10=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\8062x\left(x+1\right)+10\left(x+1\right)=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\\left(x+1\right)\left(8062x+10\right)=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x+1=0\\8062x+10=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=-1\\8062x=-10\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\left(nhận\right)\\x=\dfrac{-5}{4031}\left(nhận\right)\end{matrix}\right.\)

Vậy: \(S=\left\{-1;\dfrac{-5}{4031}\right\}\)

câu này làm ntn :)

1/

a/ ĐKXĐ: ...

\(A=\frac{\left(\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}{\left(1-\sqrt{x}\right)\left(1+\sqrt{x}\right)}+\frac{\sqrt{x}\left(\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}{\left(\sqrt{x}+1\right)\left(x-\sqrt{x}+1\right)}\)

\(=\left(2\sqrt{x}-1\right)\left(\frac{x-\sqrt{x}+1+\sqrt{x}\left(1-\sqrt{x}\right)}{\left(1-\sqrt{x}\right)\left(x-\sqrt{x}+1\right)}\right)\)

\(=\frac{2\sqrt{x}-1}{\left(1-\sqrt{x}\right)\left(x-\sqrt{x}+1\right)}\)

Câu b không rút gọn được, lập phương lên thì biểu thức là nghiệm của pt \(x^3+6x-6=0\) ko có nghiệm đẹp

Bài 2:

a/ ĐKXĐ: \(x\ge2\)

\(\Leftrightarrow\sqrt{\left(x-1\right)\left(x-2\right)}-\sqrt{x-2}-\sqrt{\left(x-1\right)\left(x+3\right)}+\sqrt{x+3}=0\)

\(\Leftrightarrow\sqrt{x-2}\left(\sqrt{x-1}-1\right)-\sqrt{x+3}\left(\sqrt{x-1}-1\right)=0\)

\(\Leftrightarrow\left(\sqrt{x-2}-\sqrt{x+3}\right)\left(\sqrt{x-1}-1\right)=0\)

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

2/

b/

\(\Leftrightarrow\sqrt{\left(x-4\right)\left(2x-1\right)}+3\sqrt{2x-1}=\sqrt{\left(x+11\right)\left(2x-1\right)}\)

Để phương trình đã cho xác định thì:

\(\left\{{}\begin{matrix}\left(x-4\right)\left(2x-1\right)\ge0\\2x-1\ge0\\\left(x+11\right)\left(2x-1\right)\ge0\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}x\ge4\\x\le\frac{1}{2}\left(1\right)\end{matrix}\right.\\x\ge\frac{1}{2}\left(2\right)\end{matrix}\right.\)

Từ (1) và (2) \(\Rightarrow x=\frac{1}{2}\) thay vào pt thấy thỏa mãn

Vậy \(x=\frac{1}{2}\) là nghiệm duy nhất

c/ ĐKXĐ: ...

\(\Leftrightarrow x^2-2x+1+2017x-2016-2\sqrt{2017x-2016}+1=0\)

\(\Leftrightarrow\left(x-1\right)^2+\left(\sqrt{2017x-2016}-1\right)^2=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-1=0\\\sqrt{2017x-2016}-1=0\end{matrix}\right.\) \(\Rightarrow x=1\)

d/ \(\Leftrightarrow\sqrt{\left(1+x^2\right)^3}-1+3x^4-4x^3=0\)

\(\Leftrightarrow\frac{\left(1+x^2\right)^3-1}{\left(1+x^2\right)^3+1}+x^2\left(3x^2-4x\right)=0\)

\(\Leftrightarrow\frac{x^6+3x^4+3x^2}{\left(1+x^2\right)^2+1}+x^2\left(3x^2-4x\right)=0\)

\(\Leftrightarrow x^2\left(\frac{x^4+3x^3+3}{x^4+2x^2+2}+3x^2-4x\right)=0\)

\(\Rightarrow x=0\)

Nhận xét: Tổng các hệ số của phương trình bằng 0 => phương trình có 1 nghiệm là 1

=> vế trái có nhân tử (x - 1)

pt <=> (x⁴ - 1 ) + (2015x³ - 2015x²) - (2015x - 2015)  = 0

<=> (x-1)(x+1).(x² + 1) + 2015x²(x - 1) - 2015.(x - 1) = 0

<=> (x - 1).[(x+1).(x² + 1) + 2015x² - 2015] = 0

<=> (x -1). [(x+1).(x² + 1) + 2015(x² - 1)] = 0

<=> (x -1). [(x+1).(x² + 1) + 2015(x - 1)(x+1)] = 0

<=> (x -1).(x+1).(x² + 1 + 2015x - 2015 ) = 0  

<=> x - 1 = 0 hoặc  x+ 1 = 0 hoặc x² + 1 + 2015x - 2015  = 0

+) x - 1 = 0 <=> x = 1

+) x + 1 = 0 <=> x = -1

+) x² + 1 + 2015x - 2015 = 0 <=> x² + 2015x - 2014 = 0 

<=> x² +2.x. \(\frac{2015}{2}\) + \(\left(\frac{2015}{2}\right)^2\) - \(\left(\frac{2015}{2}\right)^2\)   - 2015 = 0

<=> \(\left(x-\frac{2015}{2}\right)^2=\frac{2015^2+4030}{2}\)

<=>  \(x-\frac{2015}{2}=\sqrt{\frac{2015^2+4030}{2}}\) hoặc \(x-\frac{2015}{2}=-\sqrt{\frac{2015^2+4030}{2}}\)

<=> \(x=\frac{2015}{2}+\sqrt{\frac{2015^2+4030}{2}}\)hoặc \(x=\frac{2015}{2}-\sqrt{\frac{2015^2+4030}{2}}\)

Vậy pt có 4 nghiệm...

chính xác nè bạn nhớ sai ruj:

x⁴+2015x²+2014x+2015=0

<=>x⁴-x+2015x²+2015x+2015=0

<=>x(x³-1)+2015(x²+x+1)=0

<=>x(x-1)(x²+x+1)+2015(x²+x+1)=0

<=>(x²+x+1)[x(x-1)-2015]=0

<=>(x²+x+1)(x²-x-2015)=0

<=>x²+x+1=0 hoặc x²-x-2015=0

*x²+\(2x.\frac{1}{2}\)+\(\frac{1}{4}+\frac{3}{4}\)=0 

<=>(x+1/2)²+3/4=0(vô lí)

*x²-\(2x.\frac{1}{2}+\frac{1}{4}-\frac{8061}{4}\)

<=>(x-1/2)²-8061/4=0

<=>(x-1/2)²           =8061/4

<=>x-1/2              =\(\sqrt{\frac{8061}{4}}\)

<=>x                    =\(\sqrt{\frac{8061}{4}+}\frac{1}{2}\)