\(\sqrt{x}-\sqrt{x+1}-\sqrt{x+4}+\sqrt{x+9}=0;ĐK:x\ge4\)

\(\Leftrightarrow\sqrt{x}+\sqrt{x+9}=\sqrt{x+1}-\sqrt{x+4}\)

\(\Leftrightarrow2x+9+2\sqrt{x^2+9x}=2x-5+2\sqrt{x^2-5x+4}\)

\(\leftrightarrow14+2\sqrt{x^2+9x}=2\sqrt{x^2-5x+4}\leftrightarrow7+\sqrt{x^2+9x}=\sqrt{x^2-5x+4}\)

\(\leftrightarrow49+14\sqrt{x^2+9x}+x^2+9x=x^2-5x+4\)

\(\leftrightarrow14\sqrt{x^2+9x}=-14x-45\)

\(\leftrightarrow\hept{\begin{cases}196.x^2+9x=196x^2+1260x+2025\\-14x-45\ge0\end{cases}}\Leftrightarrow\hept{\begin{cases}504x=2025\\x\le\frac{-45}{14}\end{cases}\leftrightarrow x=\frac{225}{56}}\) loại

-> PT vô nghiệm

mk ko bt 123

\(\Leftrightarrow\dfrac{x+3+x-1+2\sqrt{\left(x+3\right)\left(x-1\right)}}{x+3-x+1}=\dfrac{13-x^2}{4}\)

\(\Leftrightarrow2x+2+2\sqrt{\left(x+3\right)\left(x-1\right)}=13-x^2\)

\(\Leftrightarrow\sqrt{4\left(x+3\right)\left(x-1\right)}=13-x^2-2x-2=-x^2-2x+11\)

=>\(x\simeq1,37\)

\(x+\sqrt{5+\sqrt{x-1}}=6\)

Đk:\(x\ge1\)

\(pt\Leftrightarrow\sqrt{5+\sqrt{x-1}}=6-x\)

\(\Leftrightarrow5+\sqrt{x-1}=x^2-12x+36\)

\(\Leftrightarrow\sqrt{x-1}=x^2-12x+31\)

\(\Leftrightarrow x-1=x^4-24x^3+206x^2-744x+961\)

\(\Leftrightarrow-x^4+24x^3-206x^2+745x-962=0\)

\(\Leftrightarrow-\left(x^2-13x+37\right)\left(x^2-11x+26\right)=0\)

\(\Rightarrow x=-\frac{\sqrt{17}-11}{2}\) (thỏa)

sai đề