Question

Giúp mik ạ

Answer 1

a: Thay x=4 vào A, ta được:

\(A=\dfrac{2-1}{2+3}=\dfrac{1}{5}\)

b: \(B=\dfrac{x-11\sqrt{x}-12+x+6\sqrt{x}+9-x+6\sqrt{x}-9}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}\)

\(=\dfrac{x+\sqrt{x}-12}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}=\dfrac{\sqrt{x}+4}{\sqrt{x}+3}\)