Solve for x in the equation 3 x squared minus 18 x plus 5 is equal to 47

Subtract 47 from both sides to get 3x² − 18x − 42 = 0, then divide by 3: x² − 6x − 14 = 0. Using the quadratic formula gives x = (6 ± √(36 + 56))/2 = (6 ± √92)/2 = 3 ± √23. So the solutions are x = 3 ± √23, choice D.

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