[tex]\sqrt{a+\sqrt{b}}\sqrt{a-\sqrt{b}}\sqrt{a^2-b}=[/tex]
[tex]\sqrt{(a+\sqrt{b})}\sqrt{(a-\sqrt{b})}\sqrt{(a+\sqrt{b})(a-\sqrt{b})}=[/tex]
[tex]\bigg(\sqrt{(a+\sqrt{b})}\bigg)^2\bigg(\sqrt{(a-\sqrt{b})}\bigg)^2=[/tex]
[tex](a+\sqrt{b})(a-\sqrt{b})=[/tex]
[tex]\boxed{a^2-b}[/tex]
