Math Problem Statement

learn this (Consider the expression $ e^x-ln(cos^2(x))+ln(1+tan^2(x))$ and then simplify it into a single term

Solution We are given the expression:

e x − ln ⁡ ( cos ⁡ 2 ( x ) ) + ln ⁡ ( 1 + tan ⁡ 2 ( x ) ) . e x −ln(cos 2 (x))+ln(1+tan 2 (x)). Let's simplify this step by step.

Step 1: Simplifying ln ⁡ ( cos ⁡ 2 ( x ) ) ln(cos 2 (x)) We use the logarithmic property ln ⁡ ( a b )

b ln ⁡ ( a ) ln(a b )=bln(a), where a

cos ⁡ ( x ) a=cos(x) and b

2 b=2. Thus,

ln ⁡ ( cos ⁡ 2 ( x ) )

2 ln ⁡ ( cos ⁡ ( x ) ) . ln(cos 2 (x))=2ln(cos(x)). So the expression becomes:

e x − 2 ln ⁡ ( cos ⁡ ( x ) ) + ln ⁡ ( 1 + tan ⁡ 2 ( x ) ) . e x −2ln(cos(x))+ln(1+tan 2 (x)). Step 2: Simplifying ln ⁡ ( 1 + tan ⁡ 2 ( x ) ) ln(1+tan 2 (x)) Recall the trigonometric identity 1 + tan ⁡ 2 ( x )

sec ⁡ 2 ( x ) 1+tan 2 (x)=sec 2 (x). Using this identity, we have:

ln ⁡ ( 1 + tan ⁡ 2 ( x ) )

ln ⁡ ( sec ⁡ 2 ( x ) )

2 ln ⁡ ( sec ⁡ ( x ) ) . ln(1+tan 2 (x))=ln(sec 2 (x))=2ln(sec(x)). Now the expression becomes:

e x − 2 ln ⁡ ( cos ⁡ ( x ) ) + 2 ln ⁡ ( sec ⁡ ( x ) ) . e x −2ln(cos(x))+2ln(sec(x)). Step 3: Using the identity sec ⁡ ( x )

1 cos ⁡ ( x ) sec(x)= cos(x) 1 ​

Next, we use the fact that sec ⁡ ( x )

1 cos ⁡ ( x ) sec(x)= cos(x) 1 ​ . Therefore, we can rewrite ln ⁡ ( sec ⁡ ( x ) ) ln(sec(x)) as:

ln ⁡ ( sec ⁡ ( x ) )

ln ⁡ ( 1 cos ⁡ ( x ) )

− ln ⁡ ( cos ⁡ ( x ) ) . ln(sec(x))=ln( cos(x) 1 ​ )=−ln(cos(x)). Substituting this into the expression, we get:

e x − 2 ln ⁡ ( cos ⁡ ( x ) ) + 2 ( − ln ⁡ ( cos ⁡ ( x ) ) )

e x − 2 ln ⁡ ( cos ⁡ ( x ) ) − 2 ln ⁡ ( cos ⁡ ( x ) ) . e x −2ln(cos(x))+2(−ln(cos(x)))=e x −2ln(cos(x))−2ln(cos(x)). This simplifies further to:

e x − 4 ln ⁡ ( cos ⁡ ( x ) ) . e x −4ln(cos(x)). Final Simplified Expression: Thus, the simplified expression is:

e x − 4 ln ⁡ ( cos ⁡ ( x ) ) . e x −4ln(cos(x)).)

Solution

Let's walk through the solution step by step to simplify the given expression exln(cos2(x))+ln(1+tan2(x))e^x - \ln(\cos^2(x)) + \ln(1 + \tan^2(x)).

Step 1: Simplifying ln(cos2(x))\ln(\cos^2(x))

Using the logarithmic property ln(ab)=bln(a)\ln(a^b) = b \ln(a), we have: ln(cos2(x))=2ln(cos(x)).\ln(\cos^2(x)) = 2 \ln(\cos(x)). So the expression becomes: ex2ln(cos(x))+ln(1+tan2(x)).e^x - 2 \ln(\cos(x)) + \ln(1 + \tan^2(x)).

Step 2: Simplifying ln(1+tan2(x))\ln(1 + \tan^2(x))

Using the trigonometric identity 1+tan2(x)=sec2(x)1 + \tan^2(x) = \sec^2(x), we get: ln(1+tan2(x))=ln(sec2(x))=2ln(sec(x)).\ln(1 + \tan^2(x)) = \ln(\sec^2(x)) = 2 \ln(\sec(x)). Now the expression is: ex2ln(cos(x))+2ln(sec(x)).e^x - 2 \ln(\cos(x)) + 2 \ln(\sec(x)).

Step 3: Simplifying ln(sec(x))\ln(\sec(x))

Since sec(x)=1cos(x)\sec(x) = \frac{1}{\cos(x)}, we can rewrite ln(sec(x))\ln(\sec(x)) as: ln(sec(x))=ln(1cos(x))=ln(cos(x)).\ln(\sec(x)) = \ln\left(\frac{1}{\cos(x)}\right) = - \ln(\cos(x)). Substitute this into the expression: ex2ln(cos(x))+2(ln(cos(x))).e^x - 2 \ln(\cos(x)) + 2 (- \ln(\cos(x))). This simplifies further to: ex2ln(cos(x))2ln(cos(x))=ex4ln(cos(x)).e^x - 2 \ln(\cos(x)) - 2 \ln(\cos(x)) = e^x - 4 \ln(\cos(x)).

Final Simplified Expression:

Thus, the final simplified expression is: ex4ln(cos(x)).e^x - 4 \ln(\cos(x)).

Would you like further details on any of the steps?


Here are 5 related questions to explore further:

  1. What are some properties of logarithms that are useful in simplifying expressions?
  2. How does the identity 1+tan2(x)=sec2(x)1 + \tan^2(x) = \sec^2(x) arise from the Pythagorean identities?
  3. Can this expression ex4ln(cos(x))e^x - 4 \ln(\cos(x)) be differentiated? What would its derivative be?
  4. How would the expression change if cos2(x)\cos^2(x) were replaced by sin2(x)\sin^2(x)?
  5. What happens to the expression when x=0x = 0?

Tip: Always keep logarithmic properties handy—they are essential for simplifying complex expressions.

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Math Problem Analysis

Mathematical Concepts

Exponential Functions
Logarithmic Functions
Trigonometric Identities

Formulas

ln(a^b) = b ln(a)
1 + \tan^2(x) = \sec^2(x)
sec(x) = 1 / cos(x)

Theorems

Logarithmic Properties
Trigonometric Identities

Suitable Grade Level

College-Level Mathematics (Calculus I/II)