Math Problem Statement

estimate the graph of f(x)=2^x

if f’(a)=(2^(a+.000001)-2^(a-.000001))/.000002

Try to guess a formula for f’(x) when f(x)=2^x

Solution

To estimate the graph of f(x)=2xf(x) = 2^x, we recognize that it's an exponential function. The graph is continuous and increasing because 2x2^x grows as xx increases. It passes through (0,1)(0,1), since 20=12^0 = 1, and increases rapidly for positive xx. For negative values of xx, the function approaches zero but never reaches it (asymptote at y=0y = 0).

Now, let’s focus on finding a formula for f(x)f'(x).

Derivative of f(x)=2xf(x) = 2^x

You're given the difference quotient approximation for the derivative of f(x)f(x) at x=ax = a: f(a)2a+0.0000012a0.0000010.000002f'(a) \approx \frac{2^{a + 0.000001} - 2^{a - 0.000001}}{0.000002}

This form suggests the standard definition of a derivative: f(x)=limh0f(x+h)f(xh)2hf'(x) = \lim_{h \to 0} \frac{f(x + h) - f(x - h)}{2h} However, let's derive the exact formula for the derivative of 2x2^x using the rules of exponential functions.

  1. Start with the exponential function: f(x)=2xf(x) = 2^x

  2. Recall that the derivative of an exponential function of the form axa^x is: ddxax=axln(a)\frac{d}{dx} a^x = a^x \ln(a) where aa is a constant (in this case, a=2a = 2).

  3. Applying this rule to 2x2^x: f(x)=2xln(2)f'(x) = 2^x \ln(2)

So, the derivative of f(x)=2xf(x) = 2^x is: f(x)=2xln(2)f'(x) = 2^x \ln(2)

Summary:

The derivative of f(x)=2xf(x) = 2^x is: f(x)=2xln(2)f'(x) = 2^x \ln(2)

This means that the slope of the function at any point xx is proportional to the value of 2x2^x, scaled by the constant ln(2)\ln(2), which is approximately 0.6931.

Would you like more details or explanations on any part of this?


Here are five related questions to expand on this topic:

  1. How would the derivative change if f(x)=3xf(x) = 3^x instead of 2x2^x?
  2. What is the second derivative of f(x)=2xf(x) = 2^x?
  3. How does the growth rate of 2x2^x compare to exe^x?
  4. Can you explain why ln(2)\ln(2) appears in the derivative of 2x2^x?
  5. How would you estimate the tangent line at a specific point on the graph of 2x2^x?

Tip: When dealing with exponential functions, remember that the derivative involves the natural logarithm of the base.

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Math Problem Analysis

Mathematical Concepts

Calculus
Exponential Functions
Derivatives

Formulas

f'(x) = 2^x ln(2)
f'(a) ≈ (2^(a + 0.000001) - 2^(a - 0.000001)) / 0.000002
Derivative of a^x: d/dx a^x = a^x ln(a)

Theorems

Derivative of Exponential Functions
Difference Quotient

Suitable Grade Level

Grades 11-12 or early college