\(\sqrt{4-2\sqrt{3}}-\sqrt{7+4\sqrt{3}}\\ =\sqrt{4-2\sqrt{3}.1}-\sqrt{7+2.2.\sqrt{3}}\\ =\sqrt{3-2\sqrt{3}+1}-\sqrt{4+2.2.\sqrt{3}+3}\\ =\sqrt{\left(\sqrt{3}-1\right)^2}-\sqrt{\left(2+\sqrt{3}\right)^2}=\left|\sqrt{3}-1\right|-\left|2+\sqrt{3}\right|\\ =\sqrt{3}-1-2-\sqrt{3}\\ =-3\)