Question

(√3+√x)(√3-√x)
(√7-√3)(√7+√13)
(2√a-√b)(2√a+√b)

Answer 1

$1)(\sqrt{3}+\sqrt{x})(\sqrt{3}-\sqrt{x})=(\sqrt{3})^{2}-(\sqrt{x})^{2}=3-x\\\\2)(\sqrt{7}-\sqrt{3})(\sqrt{7}+\sqrt{3} )=(\sqrt{7})^{2}-(\sqrt{3})^{2}=7-3=4\\\\3)(2\sqrt{a} -\sqrt{b})(2\sqrt{a}+\sqrt{b})=(2\sqrt{a})^{2}-(\sqrt{b})^{2}=4a-b$