Bạn tham khảo nhé.
`\sqrt{7-4\sqrt{3}}-\sqrt{(7-2\sqrt{3})^2}`
`=\sqrt{4-2.2.\sqrt{3}+3}-|7-2\sqrt{3}|`
`=\sqrt{(2-\sqrt{3})^2}-7+2\sqrt{3}`
`=|2-\sqrt{3}|-7+2\sqrt{3}`
`=2-\sqrt{3}-7+2\sqrt{3}`
`=\sqrt{3}-5`
$\\$
`\sqrt{x+5}=3(x>=-5)`
`=>x+5=3^2`
`=>x=9-5`
`=>x=4(\text{Thỏa mãn})`
Vậy `x=4`
$\\$
`\sqrt{(3-4x)^2}=3`
`<=>|3-4x|=3`
`<=>[(3-4x=3),(3-4x=-3):}`
`<=>[(4x=0),(4x=6):}`
`<=>`$\left[\begin{matrix} x=0 \\ x=\dfrac{3}{2}\end{matrix}\right.$
Vậy `x\in{0;3/2}`
