Categorias: Todos - exponential - differentiation - functions - integration

por David Kedrowski 14 anos atrás

413

MAT.126 5.5

MAT.126 5.5

MAT.126 5.5 Bases Other Than e and Applications

Differentiation and Integration

A comparison of 4 rules for differentiation

Constant Rule

d/dx[e^e] = 0

Power Rule

d/dx[x^e] = e x^{e-1}

Exponential Rule

d/dx[e^x] = e^x

Logarithmic differentiation

d/dx[x^x] = x^x (1 + ln x)

Integration

When confronted with an integral of the form

S a^x dx

there are two choices.

One is to convert the exponential expression with base a to an equivalent exponential expression with base e. That is, consider

S e^{(ln a)x} dx

remembering that ln a is a constant.

The second option is to use the following integration formula,

S a^x dx = (1/ln a) a^x + C

Derivatives for Bases Other Than e

Let a be a positive real number (a<>1) and let u be a differentiable function of x.

d


  • ---[a^x] = (ln a) a^x
  • dx

    d du


  • ---[a^u] = (ln a) a^u ----
  • dx dx

    d 1

  • ---[log_a x] = --------
  • dx (ln a) x

    d 1 du

  • ---[log_a u] = -------- ---
  • dx (ln a) u dx

    Applications of Exponential Functions

    Logisitic Growth
    Continuously Compounded Interest
    Compound Interest

    Bases Other than e

    Common Logarithmic Function

    The logarithm with base 10.

    Inverse Function Properties

  • y = a^x if and only if x = log_a y

  • a^{log_a x} = x, for x > 0

  • log_a a^x = x, for all x
  • Logarithmic Properties

  • log_a 1 = 0

  • log_a xy = log_a x + log_a y

  • log_a x/y = log_a x - log_a y

  • log_a x^n = n log_a x
  • Definition of Logarithmic Function to Base a

    If a is a positive real number (a<>1) and x is any positive real number, then the logarithmic function to the base a is denoted by log_a x and is defined as

    log_a x = (1/ln a) ln x

    Laws of Exponents

  • a^0 = 1

  • a^x a^y = a^{x+y}

  • a^x / a^y = a^{x-y}

  • (a^x)^y = a^{xy}
  • Definition of Exponential Function to Base a

    If a is a positive real number (a<>1) and x is any real number, then the exponential function to the base a is denoted by a^x and is defined by

    a^x = e^{(ln a)x}

    If a=1, then y=1^x=1 is a constant function.