Đáp án+Giải thích các bước giải:
$A=\sqrt{10+5\sqrt{3}}-\sqrt{10-5\sqrt{3}}$
$A=\sqrt{5(2+\sqrt{3})}-\sqrt{5(2-\sqrt{3})}$
$A=\sqrt{5.\dfrac{4+2\sqrt{3}}{2}}-\sqrt{5.\dfrac{4-2\sqrt{3}}{2}}$
$A=\dfrac{\sqrt{5}(\sqrt{3}+1)}{\sqrt{2}}-\dfrac{\sqrt{5}(\sqrt{3}-1)}{\sqrt{2}}$
$A=\dfrac{\sqrt{15}+\sqrt{5}-\sqrt{15}+\sqrt{5}}{\sqrt{2}}$
$A=\dfrac{2\sqrt{5}}{\sqrt{2}}$
$A=\sqrt{10}$