Let y=x⅔, then y2=x4/3.
So the equation becomes y2-12y+35=0=(y-7)(y-5).
Therefore y=7 or 5 and x⅔=7 or 5.
x2=73=343 or 53=125.
x=±√343=±7√7=±18.5203 (approx) or ±√125=±5√5=±11.1803 (approx).
It's probably safer to use the positive versions of these numbers as the real solution for x.