dx/(1-x^4)^1/2=dy/(1-y^4)^1/2
を一般化して
mdx/(1-x^4)^1/2=ndy/(1-y^4)^1/2
を考えたい.
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[1]du/(1-u^4)^1/2=dz/(1-z^4)^1/2の場合
u=-{(1-z^2)/(1+z^2)}^1/2とおく.
[2]du/(1-u^4)^1/2=2dz/(1-z^4)^1/2の場合
u=2z(1-z^4)^1/2/(1+z^4)
u=(-1+2z^2+z^4)/(1+2z^2-z^4)
とおく.
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