Solving a radical equation

How do you solve this for x:
 x = √(3x - 12) + 4

x = √(3x - 12) + 4
x - 4 = √(3x - 12)   {subtracted 4 from both sides}
x² - 8x + 16 = 3x - 12   {squared both sides}
x² - 11x + 28 = 0   {subtracted 3x and added 12 to both sides}
(x - 4)(x - 7) = 0   {factored into two binomials}
x - 4 = 0 or x - 7 = 0   {set each factor equal to 0}
x = 4 or x = 7   {solved each equation for x}

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