Bài 3: a: \(x^2-7=\left(x-\sqrt{7}\right)\left(x+\sqrt{7}\right)\)d: \(x^2-16=\left(x-4\right)\left(x+4\right)\)e: \(x-81=\left(\sqrt{x}-9\right)\left(\sqrt{x}+9\right)\)Câu trả lời: Bài 3: a: \(x^2-7=\left(x-\sqrt{7}\right)\left(x+\sqrt{7}\right)\)d: \(x^2-16=\left(x-4\right)\left(x+4\right)\)e: \(x-81=\left(\sqrt{x}-9\right)\left(\sqrt{x}+9\right)\)