Câu hỏi của phương anh lê

a: Thay x=25 vào B, ta được:\(B=\dfrac{25-9}{5-3}=\dfrac{16}{2}=8\)b: \(A=\dfrac{2}{\sqrt{x}+3}-\dfrac{3}{3-\sqrt{x}}+\dfrac{x-5\sqrt{x}-3}{x-9}\)\(=\dfrac{2}{\sqrt{x}+3}+\dfrac{3}{\sqrt{x}-3}+\dfrac{x-5\sqrt{x}-3}{x-9}\)\(=\dfrac{2\sqrt{x}-6+3\sqrt{x}+9+x-5\sqrt{x}-3}{x-9}\)\(=\dfrac{x}{x-9}\)Câu trả lời: a: Thay x=25 vào B, ta được:\(B=\dfrac{25-9}{5-3}=\dfrac{16}{2}=8\)b: \(A=\dfrac{2}{\sqrt{x}+3}-\dfrac{3}{3-\sqrt{x}}+\dfrac{x-5\sqrt{x}-3}{x-9}\)\(=\dfrac{2}{\sqrt{x}+3}+\dfrac{3}{\sqrt{x}-3}+\dfrac{x-5\sqrt{x}-3}{x-9}\)\(=\dfrac{2\sqrt{x}-6+3\sqrt{x}+9+x-5\sqrt{x}-3}{x-9}\)\(=\dfrac{x}{x-9}\)