\(\sqrt{-x^2+4x+12}-\sqrt{-x^2+2x+3}=\sqrt{3}-x^2\)
\(\Leftrightarrow\sqrt{-x^2+4x+12}=\sqrt{3}-x^2+\sqrt{-x^2+2x+3}\)
\(VP=\sqrt{-x^2+4x+12}=\sqrt{-\left(x-2\right)^2+16}\le4\)
\(VT=\sqrt{3}-x^2+\sqrt{-x^2+2x+3}=\sqrt{3}-x^2+\sqrt{-\left(x-1\right)^2+4}\)
\(\le\sqrt{3}+2