Math Problem Statement

which of the following statements about the natural logarithmic function y=In(x) is FALSA? A) the range of Y=In(X) goes from - infinity to 100. b) the function In(x) is increasing wherever it is defined. c) the function In(x) is concave down wherever it is defined. d) the domain for In(x) is x>0. e) In(e^4)=4

Solution

Let's analyze each statement carefully:

A) The range of y=ln(x)y = \ln(x) goes from -infinity to 100.

  • The actual range of the natural logarithmic function y=ln(x)y = \ln(x) is from -infinity to infinity, not just up to 100. So, this statement is false.

B) The function ln(x)\ln(x) is increasing wherever it is defined.

  • The derivative of ln(x)\ln(x) is ddxln(x)=1x\frac{d}{dx} \ln(x) = \frac{1}{x}, which is positive for x>0x > 0. Therefore, the function is indeed increasing wherever it is defined. This statement is true.

C) The function ln(x)\ln(x) is concave down wherever it is defined.

  • The second derivative of ln(x)\ln(x) is d2dx2ln(x)=1x2\frac{d^2}{dx^2} \ln(x) = -\frac{1}{x^2}, which is negative for x>0x > 0. This confirms that ln(x)\ln(x) is concave down wherever it is defined. This statement is true.

D) The domain for ln(x)\ln(x) is x>0x > 0.

  • The natural logarithmic function is only defined for positive values of xx. This statement is true.

E) ln(e4)=4\ln(e^4) = 4.

  • Using the logarithmic property ln(ea)=a\ln(e^a) = a, we can see that ln(e4)=4\ln(e^4) = 4. This statement is true.

Conclusion:

The false statement is A). The range of y=ln(x)y = \ln(x) is from -infinity to infinity, not just up to 100.

Would you like any more details on this?

Here are 5 related questions to consider:

  1. What is the range of the natural logarithmic function ln(x)\ln(x)?
  2. Why is ln(x)\ln(x) concave down based on its second derivative?
  3. How do logarithmic properties simplify expressions like ln(ex)\ln(e^x)?
  4. What is the general domain of logarithmic functions?
  5. How can you prove that ln(x)\ln(x) is an increasing function using derivatives?

Tip: When solving logarithmic problems, remembering key properties like ( \ln(e^

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Math Problem Analysis

Mathematical Concepts

Logarithms
Derivative of logarithmic functions
Concavity of functions

Formulas

Derivative of ln(x): d/dx ln(x) = 1/x
Second derivative of ln(x): d²/dx² ln(x) = -1/x²
Logarithmic property: ln(e^a) = a

Theorems

Logarithmic properties
Derivative rules
Concavity of functions

Suitable Grade Level

Grades 11-12 or College-level