Answer:
x = 11
Explanation:
The student didn't divide two on both sides in the step 1. This the mistake that the student made.
The correct solution
2√( 3x + 3 ) = 12
Divide 2 on both sides,
2√( 3x + 3 ) / 2 = 12 / 2
√( 3x + 3 ) = 6
Square on both sides,
[ √( 3x + 3 ) ]² = 6²
3x + 3 = 36
3x = 36 - 3
3x = 33
x = 33 / 3
x = 11