a^2+b^2+c^2-4a-6b-8c+29=0
(a²-4a+4)+(b²-6b+9)+(c²-8c+16)=0
(a-2)²+(b-3)²+(c-4)²=0
a-2=0,b-3=0,c-4=0
a=2,b=3,c=4