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a. \(x\left(x+7\right)-\left(x-2\right)\left(x+3\right)=0\)

\(\Leftrightarrow x^2+7x-x^2-x+6=0\)

\(\Leftrightarrow6\left(x+1\right)=0\)

\(\Leftrightarrow x+1=0\)

\(\Leftrightarrow x=-1\)

b. \(\left(x+2\right)^2-\left(x^2-4\right)=0\)

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

\(\Leftrightarrow4\left(x+2\right)=0\)

\(\Leftrightarrow x+2=0\)

\(\Leftrightarrow x=-2\)

naturalize

Hình như sai á bạn, ĐK câu c chị ở trên làm đúng r á

Câu cuối mình sai nha
\(-5x-10\ge0\) \(\Leftrightarrow\left\{{}\begin{matrix}-\left(5x+10\right)\ge0\\-5x-10\ge0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\le2\\x\ge-2\end{matrix}\right.\) \(\Leftrightarrow-2\le x\le2\)

Câu a sai ĐK r

a. \(\sqrt{\left(x-2\right)\left(x-6\right)}\) có nghĩa \(\Leftrightarrow\left\{{}\begin{matrix}x-2\ge0\\x-6\ge0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\ge2\\x\ge6\end{matrix}\right.\) \(\Leftrightarrow x\ge6\)

b. \(\sqrt{1-x^2}\) có nghĩa \(\Leftrightarrow1-x^2\ge0\) \(\Leftrightarrow\left\{{}\begin{matrix}1-x\ge0\\x+1\ge0\end{matrix}\right.\) \(\Leftrightarrow-1\le x\le1\)

\(\sqrt{-5x-10}\) có nghĩa \(\Leftrightarrow-5x-10\ge0\Leftrightarrow-5x\ge10\Leftrightarrow x\ge-2\)