√(3x+1) = 3 + √(x-4)
Square both sides to get: 3x + 1 = 9 + 6√(x-4) + x - 4
2x - 4 = 6√(x-4)
Square both sides again: 4x2 - 16x + 16 = 36(x-4)
4x2 - 16x + 16 = 36x - 144
4x2 - 52x + 160 = 0
x2 - 13x + 40 = 0
(x-8)(x-5) = 0
x = 8 or x = 5
Substituting each of these values into the ORIGINAL equation, we see that they both work.
So, the solutions are 8 and 5.