`y10000`
`a )`
`ĐK : x ≥ 0`
$\sqrt{x}$ `= 12`
`<=>` $\sqrt{( x )²}$ `= 12²`
`<=> x = 144` `( TM )`
`b )`
$\text{ĐK : x ≥ 0}$
`2`$\sqrt{x}$ `+ 1 = 5`
`<=> 2`$\sqrt{x}$ `= 4`
`<=>` $\sqrt{x}$ `= 2`
`<=> $\sqrt{( x )²}$ `=2²`
`<=> x = 4`. `( TM )`
`c )`
$\text{ĐK : x ≥ 2}$
`4`$\sqrt{x - 2}$ `- 2 = 14`
`<=>` 4`$\sqrt{x - 2}$ `=16`
`<=>` $\sqrt{x - 2}$ `= 4`
`<=> x - 2 = 16`
`<=> x = 18` `( TM )`
