a) $\sqrt{x²-4x+4}$ = 10
⇔ $\sqrt{(x-2)²}$ = 10
⇔|x - 2| = 10
*TH1: x - 2 $\geq$ 0 ⇔ x $\geq$ 2
x - 2 = 10
⇔ x = 12 (thỏa mãn x $\geq$ 2)
*TH2: x - 2 < 0 ⇔ x < 2
2 - x = 10
⇔ x = 2 - 10
⇔ x = -8 (thỏa mãn x < 2)
b) $\sqrt{9x+9}$ + 2$\sqrt{4x+4}$ - 2$\sqrt{x+1}$ = 25
⇔ $\sqrt{9(x+1)}$ + 2$\sqrt{4(x+1)}$ - 2$\sqrt{x+1}$ = 25
⇔ 3$\sqrt{x+1}$ + 4$\sqrt{x+1}$ - 2$\sqrt{x+1}$ = 25
⇔ 5$\sqrt{x+1}$ = 25
⇔ $\sqrt{x+1}$ = 5
⇔ x + 1 = 25
⇔ x = 24
