Answer:
(a) [tex]\displaystyle \int {\frac{\sec x \tan x}{1 + \sec x}} \, dx = \boxed{ \ln | 1 + \sec x | + C }[/tex]
General Formulas and Concepts:
Calculus
Differentiation
- Derivatives
- Derivative Notation
Derivative Property [Addition/Subtraction]:
[tex]\displaystyle (u + v)' = u' + v'[/tex]
Derivative Rule [Basic Power Rule]:
- f(x) = cxⁿ
- f’(x) = c·nxⁿ⁻¹
Integration
Integration Methods: U-Substitution and U-Solve
Step-by-step explanation:
Step 1: Define
Identify given.
[tex]\displaystyle \int {\frac{\sec x \tan x}{1 + \sec x}} \, dx[/tex]
Step 2: Integrate Pt. 1
Identify variables for u-substitution/u-solve.
- Set u:
[tex]\displaystyle u = 1 + \sec x[/tex] - [u] Differentiate [Derivative Rules, Properties, and Trigonometric Differentiation]:
[tex]\displaystyle du = \sec x \tan x \ dx[/tex] - [du] Rewrite [U-Solve]:
[tex]\displaystyle dx = \cos x \cot x \ du[/tex]
Step 3: Integrate Pt. 2
- [Integral] Apply Integration Method [U-Solve]:
[tex]\displaystyle \begin{aligned}\int {\frac{\sec x \tan x}{1 + \sec x}} \, dx & = \int {\frac{\sec x \tan x \cos x \cot x}{u}} \, du\end{aligned}[/tex] - [Integrand] Simplify:
[tex]\displaystyle \begin{aligned}\int {\frac{\sec x \tan x}{1 + \sec x}} \, dx & = \int {\frac{\sec x \tan x \cos x \cot x}{u}} \, du \\& = \int {\frac{1}{u}} \, du \\\end{aligned}[/tex] - [Integral] Apply Logarithmic Integration:
[tex]\displaystyle \begin{aligned}\int {\frac{\sec x \tan x}{1 + \sec x}} \, dx & = \int {\frac{\sec x \tan x \cos x \cot x}{u}} \, du \\& = \int {\frac{1}{u}} \, du \\& = \ln | u | + C \\\end{aligned}[/tex] - [u] Back-substitute:
[tex]\displaystyle \begin{aligned}\int {\frac{\sec x \tan x}{1 + \sec x}} \, dx & = \int {\frac{\sec x \tan x \cos x \cot x}{u}} \, du \\& = \int {\frac{1}{u}} \, du \\& = \ln | u | + C \\& = \boxed{ \ln | 1 + \sec x | + C } \\\end{aligned}[/tex]
∴ we have used substitution to find the indefinite integral.
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Topic: AP Calculus AB/BC (Calculus I/I + II)
Unit: Integration