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Mathematics Dictionary
Dr. K. G. Shih

Figure 337 : Pascal triangle

  • Q01 | - Diagram : Chebyshev's polynomials in Pascal triangle
  • Q02 | - Chebyshev's polynomials in quadratical polynomial
  • Q03 | - Chebyshev's polynomials in 3rd degrees polynomial
  • Q04 | - Chebyshev's polynomials in 4th degrees polynomial
  • Q05 | -


Q01. Diagram : Fibonacci sequences in Pascal triangle


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Q02. Chebyshev's polynomials in 2nd degrees polynomial

   +1 
   +1  1
   +1  2  1*
   +1  3*  3  1
   +1* 4  6  6  1
    1  5 10 10  5  1
   1. Definition

      a. The 2nd degree Chebyshev's poynomial is x^2 + 3*x + 1
      b. The coefficients are 1*, 3*, 1* in Pascal triangle

   2. Chebyshev's equation

      a. Equation is x^2 + 3*x + 1 = 0
      b. Solution is x = -4*cos(k*pi/5)^2 and k = 1, 2
      c. Use calculator, we have

         k = 1 and x = -4*cos(1*pi/5)^2 = -2.6180
         k = 2 and x = -4*cos(2*pi/5)^2 = -0.3820

      d. Verify using quadratic formula

         x = (-3 + Sqr(3^2 - 4*1*1))/4 = -0.3820
         x = (-3 - Sqr(3^2 - 4*1*1))/4 = -2.6180

   3. Question : What is the number 5 in x = -4*cos(k*pi/5)^2 ?

      Answer : Thery are the 1's with +1 in Pascal triangle

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Q03. Chebyshev's polynomials in 3rd degrees polynomial

   +1 
   +1  1
   +1  2  1
   +1  3  3  1*
   +1  4  6* 6  1
   +1  5*10 10  5  1
   +1* 6 15 20 15  6  1
    1  7 21 35 35 21  7  1
   1. Definition of 3nd degree Chebyshev's poynomial 

      a. The polynomial is x^3 + 5*x^2 +6*x + 1
      b. The coefficients are 1*, 5* 6*, 1* in Pascal triangle

   2. Chebyshev's equation

      a. Equation is x^3 + 5*x^2 + 6*x + 1 = 0
      b. Solution is x = -4*cos(k*pi/7)^2 and k = 1, 2, 3
      c. Use calculator, we have

         k = 1 and x = -4*cos(1*pi/7)^2 = -3.2470
         k = 2 and x = -4*cos(2*pi/7)^2 =
         K = 3 and x = -4*cos(3*pi/7)^2 =

      d. Verify by substituting roots into polynomial

         (-3.2470)^3 + 5*(-3.2470)^2 + 6*(-3.2470) + 1
         = -34.2332 + 52.7150 - 19.4820 + 1
         = -0.0001

   3. Question : What is the number 7 in x = -4*cos(k*pi/7)^2 ?

      Answer : Thery are the 1's with +1 in Pascal triangle

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Q04. Chebyshev's polynomials in 4th degrees polynomial

   +1 
   +1   1
   +1   2   1
   +1   3   3   1
   +1   4   6   6   1*
   +1   5  10  10*  5   1
   +1   6  15* 20  15   6   1
   +1   7* 21  35  35  21   7   1
   +1*  8  28  56  70  56  28   8   1
    1   9  36  84 126 126  84  36   9   1
   1. Definition of 3nd degree Chebyshev's poynomial 

      a. The polynomial is xx^4 + 7*x^3 + 15*x^2 + 10*x + 1
      b. The coefficients are 1*, 7* 15*, 10*, 1* in Pascal triangle

   2. Chebyshev's equation

      a. Equation is x^4 + 7*x^3 + 15*x^2 + 10*x + 1 = 0
      b. Solution is x = -4*cos(k*pi/9)^2 and k = 1, 2, 3, 4
      c. Use calculator, we have

         k = 1 and x = -4*cos(1*pi/9)^2 = -3.5321
         k = 2 and x = -4*cos(2*pi/9)^2 =
         K = 3 and x = -4*cos(3*pi/9)^2 =
         k = 4 and x = -4*cos(4*pi/9)^2 =

      d. Verify by substituting roots into polynomial

         (-3.5321)^4+7*(-3.5321)^3+15*(-3.5321)^2+10*(-3.5321)+1
         = 155.6439 -308.4587 + 187.1360 - 35.3210 + 1
         = 0.0002

   3. Question : What is the number 9 in x = -4*cos(k*pi/9)^2 ?

      Answer : Thery are the 1's with +1 in Pascal triangle

   4. General solution for nth degree polynomial

               2nd degrees  5
               3rd degrees  7
               4th degrees  9
               5th degrees 11
               nth degrees 2*n + 1

      x = -4*cos(k*pi/(2*n+1))^2 and k = 1,2,3,4,....n

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Q05. Chebyshev's polynomials in 4th degrees polynomial

Exercises
   1. Write down the 5th degree polynomial
   2. Write down the solutions
   3. Find solution for k = 1
   4. Substitute x value into polynomial to verify

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