\(a,ĐK:x\ge0;x\le-3\\ PT\Leftrightarrow10-\left(x^2+3x\right)=3\sqrt{x^2+3x}\)
Đặt \(\sqrt{x^2+3x}=t\ge0\), PTTT:
\(10-t^2=3t\\ \Leftrightarrow t^2+3t-10=0\\ \Leftrightarrow t=2\left(t\ge0\right)\\ \Leftrightarrow x^2+3x=4\\ \Leftrightarrow x^2+3x-4=0\\ \Leftrightarrow\left[{}\begin{matrix}x=1\left(tm\right)\\x=-4\left(tm\right)\end{matrix}\right.\)
\(f,ĐK:-2\le x\le4\\ PT\Leftrightarrow\left(x+2\right)\left(4-x\right)+4\sqrt{\left(4-x\right)\left(x+2\right)}=0\)
Đặt \(\sqrt{\left(x+2\right)\left(4-x\right)}=a\ge0\), PTTT:
\(a^2+4a=0\\ \Leftrightarrow a=0\left(a\ge0\right)\\ \Leftrightarrow\left(x+2\right)\left(4-x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\left(tm\right)\\x=4\left(tm\right)\end{matrix}\right.\)
