(x-2)^2+y^2+z^2=4
(x-3/2)^2+(y-(√5)/2)^2+(z-(√10)/2)^2=6
(x-1)^2+(y-√5)^2+z^2=6
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[1]x=3s/2+2,y=(√5)s/2,z=(√10)s/2
9s^2/4+5s^2/4+10s^2/4=4
s^2=2/3,これは誤りではない.
(3s+1)^2/4+5(s-1)^2/4+10(s-1)^2/4=6
(3s+2)^2/4+5(s-2)^2/4+10s^2/4=6
(3s+1)^2+5(s-1)^2+10(s-1)^2=24
(3s+2)^2+5(s-2)^2+10s^2=24
24s^2-24s+16=24
24s^2-8s+24=24は満たさない.
[2]x=3t/2+1,y=(√5)t/2+√5,z=(√10)t/2
9t^2/4+5t^2/4+10t^2/4=6,t^2=1
(3t-2)^2/4+5(t+2)^2/4+10t^2/4=4
(3t-1)^2/4+5(t+1)^2/4+10t^2/4=4
はNG.
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