Question

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Answer 1

a: Khi x=20 thì \(A=\dfrac{20+5}{\sqrt{20}}=\dfrac{25}{2\sqrt{5}}=\dfrac{5\sqrt{5}}{2}\)

b: \(B=\dfrac{x-3\sqrt{x}+4-\sqrt{x}}{\sqrt{x}\left(\sqrt{x}-2\right)}=\dfrac{\left(\sqrt{x}-2\right)^2}{\sqrt{x}\left(\sqrt{x}-2\right)}=\dfrac{\sqrt{x}-2}{\sqrt{x}}\)

c: \(B\cdot\sqrt{x}=x-6\sqrt{x}+8\)

=>x-6*căn x+8=căn x-2

=>x-7căn x+10=0

=>(căn x-2)(căn x-5)=0

=>căn x-5=0

=>x=25