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  1. integral of lnx ln(1-x) from 0 to 1

    integral of lnx ln(1-x) from 0 to 1

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  3. Permutation group (Symmetric group)

    Permutation group (Symmetric group)

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  4. Integral of 1/(x^2+1) by using complex number

    Integral of 1/(x^2+1) by using complex number

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    4
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  7. The existence proof of eigenvectors and eigenvalues

    The existence proof of eigenvectors and eigenvalues

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  8. Integral of 1/(1+x^2)^2 (substitution)

    Integral of 1/(1+x^2)^2 (substitution)

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    3
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  10. How to put 20 equilateral triangles on sphere

    How to put 20 equilateral triangles on sphere

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  11. sinx+sin2x+sin3x+...+sin nx, cosx+cos2x+cos3x+cos 4 x+...+cos nx

    sinx+sin2x+sin3x+...+sin nx, cosx+cos2x+cos3x+cos 4 x+...+cos nx

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  13. Prove Method of infinite Descent : square 2 is irrational

    Prove Method of infinite Descent : square 2 is irrational

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    2
  14. Prove Method of infinite Descent : no nontrivial solutions x^2+y^2=3z^2

    Prove Method of infinite Descent : no nontrivial solutions x^2+y^2=3z^2

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  15. Prove Method of infinite Descent (Vieta's jumping) : (4a^2-1)^2/(4ab-1) is integer, then a=b

    Prove Method of infinite Descent (Vieta's jumping) : (4a^2-1)^2/(4ab-1) is integer, then a=b

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  16. Prove Method of infinite Descent : square k is irrational if k is not square free

    Prove Method of infinite Descent : square k is irrational if k is not square free

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  17. Prove Method of infinite Descent (Vieta's jumping) : (a^2+b^2)/(ab+1) is square, imo1988

    Prove Method of infinite Descent (Vieta's jumping) : (a^2+b^2)/(ab+1) is square, imo1988

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  18. Normal subgroup and quotient subgroup

    Normal subgroup and quotient subgroup

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  19. There exist distinct integers x,y,z for which, x^2+y^2+z^2=14^n

    There exist distinct integers x,y,z for which, x^2+y^2+z^2=14^n

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  20. Plot Mcdonald Shape by function

    Plot Mcdonald Shape by function

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  21. zero morphism and kernel and cokernel

    zero morphism and kernel and cokernel

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    1
  23. Cauchy's theorem for the abelian group, Sylow theorem for abelian group

    Cauchy's theorem for the abelian group, Sylow theorem for abelian group

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  25. Homomorphism of ring and ideal, quotient ring

    Homomorphism of ring and ideal, quotient ring

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