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Mathematics Dictionary
Dr. K. G. Shih

Amicable Numbers


  • Q01 | - Diagram of y = (x - 1)^3/(2*x)
  • Q02 | - Definition of asymptote
  • Q03 | - Find asymptote of y=((x - 1)^3)/(2*x)
  • Q04 | - Find signs of y' and y" from diagram
  • Q05 | - Find zero, critical points and inflextion of y = ((x - 1)^3)/(2*x)
  • Q06 | - Properties of y = ((x - 1)^3)/(2*x)

  • Q01. Diagram of y = (x - 1)^3/(2*x)

    The diagram of Y=((x-1)^3)/(2*x)

    aaa.gif

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    Q02. Definition of asymptotes

    Deifintion
      1. Vertical asymptote ...... x = a if f(a) = ∝
      2. Horizontal asymptote .... y = b if f(x)=b as x = ∝
      3. Oblique asymptote ....... y = F(x) when x = ∝

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    Q03. Find asymptote of y=((x-1)^3)/(2*x)

    Sketch program
    More examples
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    Q4. Find signs of y' and y" from diagram

    Asymptotes
    • We get Vertical asymptote : x=0 and y=infinite
    • We get Oblique asymptote : y=(x^2-3*x+3)/2 and x=infinite
    Signs of y' and y"
    • We can estimate the extreme points if y' = 0
    • We can get the point of inflexion if y" = 0

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    Q5. Find zero, critical points and inflextion of y = ((x-1)^3)/(2*x)

    Solution
    • Value of zero : x1 = 1 and y = 0
    • Critical points at y'=0
      • y'=(3*(x-1)^2)*(2*x)) - 2*(x-1)^3)/(4*x^2)
      • y'=((x-1)^2)*(6*x-2*(x-1))/(4*x^2)
      • y'=((x-1)^2)*(4*x+2))/(4*x^2)
      • y'=0 and x2=1 or x3=-1/2
      • Critical point is at x3=-1/2
    • Point of inflextion at y"=0
      • y" = ?
      • y" = 0 at x2 = 1
      • Point of inflextion at x2 = 1

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    Q6. Properties of y = ((x - 1)^3)/(2*x)

    Answer
    • y-intercept : None
    • Signs of y
      • Domain x < 0 : y is positive
      • Domain x = 0 : No exist and it has asymptote
      • Domain x between 0 and 1 : y is negative
      • Domain x > 1 : y is positive
    • Signs of y'
      • Domain x < x3 : The curve is decreasing (y' less than 0)
      • Domain x3 < x < 0 : The curve is increasing (y' greater than 0)
      • Domain at x = x3 : It is a minimum point (y'=0)
      • No domain at x=0 (asymptote)
      • Domain x greater than 0 curve is increasing (y' greater than zero)
    • Signs of y"
      • Domain x less than 0 curve concave upward (y" is positive)
      • Domain between 0 and x = 1 curve concave downward (y" is negative)
      • Domain at x greater then 1 curve concave upward (y" is positive)
      • Domain at x = 1 it is point of inflextion (y" = 0)
    • Range : y=-infinite to y=positive infinite
    • For large abs(x) the curve approaches a parabola (aymptote)

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    Copyright © Dr. K. G. Shih, Nova Scotia, Canada.

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