Math Problem Statement

Let x be a real number lying in the interval (0, 1), Which of the following statements is false? (Recall that ln = log_e). The statements involve comparisons of exponential and logarithmic expressions.

Solution

The question in the image asks which of the following statements is false, where xx is a real number lying in the interval (0,1)(0, 1), and it provides five options.

Let's evaluate each one:

  1. ex<ee^x < e:

    • Since x(0,1)x \in (0, 1), exe^x will always be less than ee because exponentiating a number less than 1 results in a value less than ee. So, this statement is true.
  2. ex<1ee^{-x} < \frac{1}{e}:

    • Here ex=1exe^{-x} = \frac{1}{e^x}. Since x(0,1)x \in (0, 1), exe^x is between 11 and ee, so 1ex\frac{1}{e^x} (which is exe^{-x}) is between 1e\frac{1}{e} and 11, meaning exe^{-x} is greater than 1e\frac{1}{e}. Thus, the statement ex<1ee^{-x} < \frac{1}{e} is false.
  3. ln(x)<0\ln(x) < 0:

    • Since x(0,1)x \in (0, 1), ln(x)\ln(x) is negative because the logarithm of any number less than 1 is negative. So, this statement is true.
  4. ex<1e^{-x} < 1:

    • Since ex=1exe^{-x} = \frac{1}{e^x}, and ex>1e^x > 1 for x(0,1)x \in (0, 1), this implies exe^{-x} is indeed less than 1. So, this statement is true.
  5. ln(1x)>0\ln\left( \frac{1}{x} \right) > 0:

    • Since x(0,1)x \in (0, 1), 1x>1\frac{1}{x} > 1, and the logarithm of a number greater than 1 is positive. So, this statement is true.

Conclusion:

The false statement is ex<1ee^{-x} < \frac{1}{e}, which corresponds to the second option.

Would you like more details or explanations? Here are 5 related questions to expand the topic:

  1. What is the behavior of the exponential function exe^x when xx is negative?
  2. How does the logarithmic function behave for values in the interval (0,1)(0, 1)?
  3. Why is exe^{-x} always greater than 1e\frac{1}{e} for x(0,1)x \in (0, 1)?
  4. How do exponential and logarithmic functions relate to each other in terms of inverse functions?
  5. What are the properties of ln(x)\ln(x) when x0+x \to 0^+?

Tip:

When working with logarithmic inequalities, always keep in mind the domain restrictions to avoid undefined results (e.g., ln(x)\ln(x) is only defined for x>0x > 0).

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Math Problem Analysis

Mathematical Concepts

Exponential functions
Logarithmic functions
Inequalities

Formulas

e^x
e^{-x} = 1/e^x
ln(x)

Theorems

Properties of exponential functions
Properties of logarithmic functions

Suitable Grade Level

Grades 11-12 (High school)