`#Mon`
`\sqrt{4x^2+5x+1}-2\sqrt{x^2-x+1}=9x-3`
`<=>(\sqrt{4x^2+5x+1}-2\sqrt{x^2-x+1})(\sqrt{4x^2+5x+1}+2\sqrt{x^2-x+1})`
`=(9x-3)(\sqrt{4x^2+5x+1}+2\sqrt{x^2-x+1})`
`<=>9x-3=(9x-3)(\sqrt{4x^2+5x+1}+2\sqrt{x^2-x+1})`
`<=>(9x-3)(\sqrt{4x^2+5x+1}+2\sqrt{x^2-x+1-1}=0`
`<=>9x-3=0`
`<=>x=\frac{1}{3}`
`=>\text{ Vậy phương trình có nghiệm duy nhất là}` `x=\frac{1}{3}`