Introductory Algebra for College Students (7th Edition)

$(2\sqrt{3}+\sqrt5)(2\sqrt{3}-\sqrt5)$ Use the FOIL method to multiply the binomial. Multiply the First terms, the Outside terms, the Inside terms, and the Last terms. $(2\sqrt{3}\times2\sqrt{3})+(2\sqrt3\times(-\sqrt5))+(2\sqrt3\times\sqrt5)+(\sqrt5\times(-\sqrt5))$ Simplify. $12-2\sqrt{15}+2\sqrt{15}-5$ Combine like terms/like radicals. $7$