\(a,\sqrt{-2x+3}\) có nghĩa \(\Leftrightarrow-2x+3\ge0\Leftrightarrow-2x\ge-3\Leftrightarrow x\le\dfrac{3}{2}\)
\(b,\sqrt{-5x}\) có nghĩa \(\Leftrightarrow-5x\ge0\Leftrightarrow x\le0\)
\(c,\sqrt{-3x+7}\) có nghĩa \(\Leftrightarrow-3x+7\ge0\Leftrightarrow-3x\ge-7\Leftrightarrow x\le\dfrac{7}{3}\)
\(d,\sqrt{3x+7}\) có nghĩa \(\Leftrightarrow3x+7\ge0\Leftrightarrow3x\ge-7\Leftrightarrow x\ge-\dfrac{7}{3}\)