Converting a parametric surface to an implicit (ordinary) equation

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The parametric representation of surfaces, introduced by Gauss, consists in giving the coordinates of the points of the surface as functions of two parameters: x=φ(u,v)x=\varphi (u,v), y=ψ(u,v)y=\psi (u,v), z=ω(u,v)z=\omega (u,v).

The equation of a sphere can be represented in the form

x=asin⁡θcos⁡φ,y=asin⁡θsin⁡φ,z=acos⁡θ. x = a\sin \theta \cos \varphi , \qquad y = a\sin \theta \sin \varphi , \qquad z = a\cos \theta .

Find a similar form of the equation for an ellipsoid.

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A surface is given by the equations

x=acos⁡4ucos⁡4v,y=acos⁡4usin⁡4v,z=asin⁡4u. x = a\cos ^{4}u\cos ^{4}v, \qquad y = a\cos ^{4}u\sin ^{4}v, \qquad z = a\sin ^{4}u .

Find its equation in ordinary form.

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The same question (find the equation in ordinary form) for the surface given by the equations

x=acos⁡3ucos⁡3v,y=acos⁡3usin⁡3v,z=asin⁡3v. x = a\cos ^{3}u\cos ^{3}v, \qquad y = a\cos ^{3}u\sin ^{3}v, \qquad z = a\sin ^{3}v .
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The same question (find the equation in ordinary form) for the surface given by the equations

x=au2+v2−1u2+v2+1,y=b2uu2+v2+1,z=c2vu2+v2+1. x = a\frac{u^{2}+v^{2}-1}{u^{2}+v^{2}+1}, \qquad y = b\frac{2u}{u^{2}+v^{2}+1}, \qquad z = c\frac{2v}{u^{2}+v^{2}+1} .
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References

[ГюКу03] Гюнтер Н.М., Кузьмин Р.О. Сборник задач по высшей математике. 13-е изд., Издательство «Лань», 2003.