Solve 3 x 2 − 3 √ (2 3 √ x+4 3 √ )=0 3x2−3(23x+43)=0 by completing the square

Question

I don't know how to do it and would like an explanation of how to do it. 

Answer 1

3x^2-69x-129=0

X^2-23x-43=0

X^2-23x+529/4-43-529/4=0

(X-23/2)^2-701/4=0

(X-23/2)^2=701/4

X-23/2=+or- sqrt(701)/2

X= (23 +or- sqrt(701))/2