a, ĐK: \(x\ge2\)

\(\sqrt{2x+1}-\sqrt{x-2}=x+3\)

\(\Leftrightarrow\dfrac{x+3}{\sqrt{2x+1}+\sqrt{x-2}}=x+3\)

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

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

Phương trình vô nghiệm.

b, ĐK: \(x\ge-1\)

\(\sqrt{x+3}+2x\sqrt{x+1}=2x+\sqrt{x^2+4x+3}\)

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

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

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

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

\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x\ge0\\x+3=4x^2\end{matrix}\right.\\x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\left(tm\right)\\x=0\left(tm\right)\end{matrix}\right.\)

c, ĐK: \(x\ge-3\)

\(2\sqrt{x+3}=9x^2-x-4\)

\(\Leftrightarrow x+3+2\sqrt{x+3}+1=9x^2\)

\(\Leftrightarrow\left(\sqrt{x+3}+1\right)^2=9x^2\)

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

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

TH1: \(\left\{{}\begin{matrix}3x-1\ge0\\x+3=9x^2-6x+1\end{matrix}\right.\Leftrightarrow...\)

TH2: \(\left\{{}\begin{matrix}-3x-1\ge0\\x+3=9x^2+6x+1\end{matrix}\right.\Leftrightarrow...\)

Tự giải nha, t kh có máy tính ở đây.

câu 2 có nghiệm x=2 , liên hợp đi 

\(\Leftrightarrow\sqrt{x^2-\frac{1}{4}+\sqrt{\left(x+\frac{1}{2}\right)^2}}=\frac{1}{2}\left(2x^3+x^2+2x+1\right)\)\(\Leftrightarrow\sqrt{x^2+x+\frac{1}{4}}=\frac{1}{2}\left(2x^3+x^2+2x+1\right)\)\(\Leftrightarrow x+\frac{1}{2}=\frac{1}{2}\left(2x^3+x^2+2x+1\right)\Leftrightarrow2x+1=2x^3+x^2+2x+1\)\(\Leftrightarrow2x^3+x^2=0\Leftrightarrow\orbr{\begin{cases}x=0\\x=-\frac{1}{2}\end{cases}}\)

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

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

\(x^2+1\ge1\forall x\Rightarrow2x+1\ge0!2x+1!=2x+1\)

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

\(\left(1\right)\Leftrightarrow x+\frac{1}{2}=\frac{1}{2}\left(2x+1\right)\left(x^2+1\right)\)

\(\left(1\right)\Leftrightarrow2x+1=\left(2x+1\right)\left(x^2+1\right)\Leftrightarrow\left(2x+1\right).\left(1-\left(x^2+1\right)\right)=0\)

\(\hept{\begin{cases}2x+1=0\\-x^2=0\end{cases}\Rightarrow\hept{\begin{cases}x=-\frac{1}{2}\\x=0\end{cases}}}\)

Chúc bạn học tốt !!!

a ; \(3x-7\sqrt{x}+4=0 \) 
\(3x-3\sqrt{x}-4\sqrt{x}+4=0\)\(\left(\sqrt{x}-1\right)\left(3\sqrt{x}-4\right)=0\)
từ đó suy ra x

Bạn giải cụ thể từng câu cho mk nhé!!! :))))

a ĐK \(x\ge0\)

\(3x-7\sqrt{x}+4=0\Rightarrow\left(\sqrt{x}-1\right)\left(3\sqrt{x}-4\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}\sqrt{x}-1=0\\3\sqrt{x}-4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}\sqrt{x}=1\\\sqrt{x}=\frac{4}{3}\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=1\\x=\frac{16}{9}\end{cases}\left(tm\right)}}\)

b. ĐK \(x\ge2\)

\(\Leftrightarrow\sqrt{x+1}.\sqrt{x-1}=\sqrt{x+3}.\sqrt{x-2}\)

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

\(\Leftrightarrow x^2-1=x^2-x+6\Leftrightarrow x=5\left(tm\right)\)

Các câu còn lại tương tự

\(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{6}{x-y}+3\sqrt{y+1}=12\\\dfrac{1}{x-y}-3\sqrt{y+1}=-5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x-y=1\\3\sqrt{y+1}=6\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-y=1\\y+1=4\end{matrix}\right.\Leftrightarrow\left(x,y\right)=\left(4;3\right)\)

\(x^2+1+3x=x\sqrt{x^2+1}+3\sqrt{x^2+1}\)

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

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

\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x^2+1}=x\\\sqrt{x^2+1}=3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x^2+1=x^2\\x^2=8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}∃x̸\\x=\pm\sqrt{8}\end{matrix}\right.\)

`x^2 + 3x + 1 = (x + 3) \sqrt{x^2 + 1}`

Nghiệm của pt là `x = +- 2 \sqrt{2}`