\(a,3-\sqrt{1-16x^2}\)
\(=3-\sqrt{-\left(16x^2-1\right)}\)
\(=3-\sqrt{-\left(4x-1\right)\left(4x+1\right)}\)
Căn thức xác định khi \(\sqrt{-\left(4x-1\right)\left(4x+1\right)\ge0}\)
\(\Rightarrow\left(4x-1\right)\left(4x+1\right)\le0\)
.....
\(b,\sqrt{2x^2-6}\)
\(=\sqrt{2\left(x^2-3\right)}\)
\(=\sqrt{2\left(x-\sqrt{3}\right)\left(x+\sqrt{3}\right)}\)
Để căn thức xác định \(\Rightarrow\sqrt{2\left(x-\sqrt{3}\right)\left(x+\sqrt{3}\right)}\ge0\)
\(\Rightarrow\left(x+\sqrt{3}\right)\left(x-\sqrt{3}\right)\ge0\)
.....