Question

Giúp mình 4 câu ở dưới với

Answer 1

\(B=\dfrac{5x+15\sqrt{x}-26\sqrt{x}+26-20}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-1\right)}\)

\(=\dfrac{5x-11\sqrt{x}+6}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-1\right)}=\dfrac{\left(\sqrt{x}-1\right)\left(5\sqrt{x}-6\right)}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-1\right)}\)

\(=\dfrac{5\sqrt{x}-6}{\sqrt{x}+3}\)

n: \(B< =\dfrac{-x+9\sqrt{x}-10}{\sqrt{x}+3}\)

=>5*căn x-6<=-x+9căn x-10

=>x-4*căn x+4<=0

=>(căn x-2)^2<=0

=>căn x-2=0

=>x=4

p: \(B=\dfrac{5\sqrt{x}+15-21}{\sqrt{x}+3}=5-\dfrac{21}{\sqrt{x}+3}\)

căn x+3>=3

=>21/căn x+3<=7

=>-21/căn x+3>=-7

=>B>=-7+5=-2

Dấu = xảy ra khi x=0