p-Integrals In Theory

                                       1
      Consider a p-Integral of the form ⌠ p where p is a positive integer.
                                           dx
1
                                         ⌡x
                                         0
                        1
      Case 1: How does ⌠ p behave (converge or diverge) when 0<p<1?
                          dx
1.1
                        ⌡x
                        0
      1           1               -p+1 1
      ⌠dx = lim ⌠x-pdx = lim x  = lim  1 –a  , (1-p)>0
                                                     1-p
                +⌡              +-p+1        +1-p 1-p 
      ⌡x a 0
        p                 a 0          a a 0
      0          a
        1
        ⌠dx = 1 , ∀p∈(0, 1)
        ⌡ xp 1-p
         0
        1
        ⌠dx , 0<p<1, Converges!
      ∴ p
        ⌡x
        0
                         1
1.2   Case 2: How does   ⌠dx behave (converge or diverge) when p=1?
                         ⌡ xp
                         0
      1           1
                                   1
      ⌠dx = lim ⌠dx = lim ln(x)] = lim [(ln(1)–ln(a)]
      ⌡ x p a 0+ ⌡ x a 0 +         a a 0
                                         +

      0           a
        1
      ∴⌠ p , p=1, Diverges!
           dx
        ⌡x
        0
                         1
      Case 3: How does ⌠ p behave (converge or diverge) when p>1?
                           dx
1.3
                         ⌡x
                         0
      1           1              -p+1 1
      ⌠dx = lim ⌠x-pdx = lim x  = lim  1 –a  , (1-p)<0
                                                   1-p
                 +⌡            +-p+1       +1-p 1-p 
      ⌡x a 0
          p                a 0        a a 0
      0           a
        1
        ⌠dx , p>1, Diverges!
      ∴ p
        ⌡x
        0




                                a:pintthry.doc                               1
p-Integrals In Theory

                                          +∞
                                           ∞
      Consider a p-Integral of the form ⌠ p where p is a positive integer.
                                             dx
2
                                          ⌡x
                                           1
                        +∞
      Case 1: How does ⌠ p behave (converge or diverge) when 0<p<1?
                           dx
2.1
                         ⌡x
                         1
      +∞           b                 -p+1 b
      ⌠dx = lim ⌠x-pdx = lim x  = lim b – 1  , (1-p)>0
                                                   1-p

      ⌡ x b +∞
         p        ⌡         b +∞-p+1 1 b +∞ 1-p 1-p
       1           1
        +∞
      ∴ ⌠ p , 0<p<1, Diverges!
           dx
         ⌡x
         1
                        +∞
      Case 2: How does ⌠ p behave (converge or diverge) when p=1?
                           dx
2.2
                         ⌡x
                         1
      +∞           b
                                   b
      ⌠dx = lim ⌠dx = lim ln(x)] = lim [(ln(b)–ln(1)]
      ⌡  xp b +∞⌡ x      b +∞      1 b +∞
       1           1
        +∞
      ∴ ⌠ p , p=1, Diverges!
           dx
         ⌡x
         1
                        +∞
      Case 3: How does ⌠ p behave (converge or diverge) when p>1?
                           dx
2.3
                         ⌡x
                         1
      +∞           b             -p+1 b
      ⌠dx = lim ⌠x-pdx = lim x  = lim b – 1  , (1-p)<0
                                               1-p

      ⌡ x b +∞
          p        ⌡        b +∞-p+1 1 b +∞ 1-p 1-p
       1           1
        +∞
        ⌠dx = 1 , ∀p∈(1, +∞)
        ⌡ xp p-1
         1
       +∞
      ∴ ⌠ p , p>1, Converges!
          dx
        ⌡x
        1




                                a:pintthry.doc                               2
p-Integrals In Theory

3     Conclusions: Convergence Relations

                       1
3.1   Theorem 3.1:     ⌠dx = 1 if and only if 0<p<1.
                       ⌡ xp 1-p
                       0
                       1
3.2   Corollary 3.2:   ⌠dx Diverges ∀p≥1.
                       ⌡ xp
                     0
                     +∞
      Theorem 3.3: ⌠ p =
                        dx  1
3.3                           if and only if p>1.
                     ⌡ x p-1
                      1
                     +∞
      Corollary 3.4: ⌠ p Diverges ∀p∈(0, 1]
                        dx
3.4
                     ⌡x
                      1




                                  a:pintthry.doc        3

AP Calculus BC: p-int theory notes

  • 1.
    p-Integrals In Theory 1 Consider a p-Integral of the form ⌠ p where p is a positive integer. dx 1 ⌡x 0 1 Case 1: How does ⌠ p behave (converge or diverge) when 0<p<1? dx 1.1 ⌡x 0 1 1 -p+1 1 ⌠dx = lim ⌠x-pdx = lim x  = lim  1 –a  , (1-p)>0 1-p +⌡ +-p+1 +1-p 1-p  ⌡x a 0 p a 0 a a 0 0 a 1 ⌠dx = 1 , ∀p∈(0, 1) ⌡ xp 1-p 0 1 ⌠dx , 0<p<1, Converges! ∴ p ⌡x 0 1 1.2 Case 2: How does ⌠dx behave (converge or diverge) when p=1? ⌡ xp 0 1 1 1 ⌠dx = lim ⌠dx = lim ln(x)] = lim [(ln(1)–ln(a)] ⌡ x p a 0+ ⌡ x a 0 + a a 0 + 0 a 1 ∴⌠ p , p=1, Diverges! dx ⌡x 0 1 Case 3: How does ⌠ p behave (converge or diverge) when p>1? dx 1.3 ⌡x 0 1 1 -p+1 1 ⌠dx = lim ⌠x-pdx = lim x  = lim  1 –a  , (1-p)<0 1-p +⌡ +-p+1 +1-p 1-p  ⌡x a 0 p a 0 a a 0 0 a 1 ⌠dx , p>1, Diverges! ∴ p ⌡x 0 a:pintthry.doc 1
  • 2.
    p-Integrals In Theory +∞ ∞ Consider a p-Integral of the form ⌠ p where p is a positive integer. dx 2 ⌡x 1 +∞ Case 1: How does ⌠ p behave (converge or diverge) when 0<p<1? dx 2.1 ⌡x 1 +∞ b -p+1 b ⌠dx = lim ⌠x-pdx = lim x  = lim b – 1  , (1-p)>0 1-p ⌡ x b +∞ p ⌡ b +∞-p+1 1 b +∞ 1-p 1-p 1 1 +∞ ∴ ⌠ p , 0<p<1, Diverges! dx ⌡x 1 +∞ Case 2: How does ⌠ p behave (converge or diverge) when p=1? dx 2.2 ⌡x 1 +∞ b b ⌠dx = lim ⌠dx = lim ln(x)] = lim [(ln(b)–ln(1)] ⌡ xp b +∞⌡ x b +∞ 1 b +∞ 1 1 +∞ ∴ ⌠ p , p=1, Diverges! dx ⌡x 1 +∞ Case 3: How does ⌠ p behave (converge or diverge) when p>1? dx 2.3 ⌡x 1 +∞ b -p+1 b ⌠dx = lim ⌠x-pdx = lim x  = lim b – 1  , (1-p)<0 1-p ⌡ x b +∞ p ⌡ b +∞-p+1 1 b +∞ 1-p 1-p 1 1 +∞ ⌠dx = 1 , ∀p∈(1, +∞) ⌡ xp p-1 1 +∞ ∴ ⌠ p , p>1, Converges! dx ⌡x 1 a:pintthry.doc 2
  • 3.
    p-Integrals In Theory 3 Conclusions: Convergence Relations 1 3.1 Theorem 3.1: ⌠dx = 1 if and only if 0<p<1. ⌡ xp 1-p 0 1 3.2 Corollary 3.2: ⌠dx Diverges ∀p≥1. ⌡ xp 0 +∞ Theorem 3.3: ⌠ p = dx 1 3.3 if and only if p>1. ⌡ x p-1 1 +∞ Corollary 3.4: ⌠ p Diverges ∀p∈(0, 1] dx 3.4 ⌡x 1 a:pintthry.doc 3