a: Thay x=16 vào A, ta được:
\(A=\dfrac{2\cdot\sqrt{16}+1}{16+\sqrt{16}+1}\)
\(=\dfrac{2\cdot4+1}{16+4+1}=\dfrac{9}{21}=\dfrac{3}{7}\)
b: \(P=\left(\dfrac{1}{\sqrt{x}-1}-\dfrac{\sqrt{x}}{1-x}\right):\left(\dfrac{\sqrt{x}}{\sqrt{x}-1}-1\right)\)
\(=\left(\dfrac{1}{\sqrt{x}-1}+\dfrac{\sqrt{x}}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\right):\dfrac{\sqrt{x}-\sqrt{x}+1}{\sqrt{x}-1}\)
\(=\dfrac{\sqrt{x}+1+\sqrt{x}}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\cdot\dfrac{\sqrt{x}-1}{1}\)
\(=\dfrac{2\sqrt{x}+1}{\sqrt{x}+1}\)
Đúng 0
Bình luận (0)
