Substitution to evaluate the indefinite integral

1 answer:

3 0

Answer:

$\displaystyle \int {e^{5x}} \, dx = \boxed{ \frac{e^{5x}}{5} + C }$

General Formulas and Concepts:
Calculus

Differentiation

Derivative Property [Multiplied Constant]:
$\displaystyle (cu)' = cu'$
Derivative Rule [Basic Power Rule]:

Integration

Integration Rule [Reverse Power Rule]:
$\displaystyle \int {x^n} \, dx = \frac{x^{n + 1}}{n + 1} + C$

Integration Property [Multiplied Constant]:
$\displaystyle \int {cf(x)} \, dx = c \int {f(x)} \, dx$

Integration Methods: U-Substitution

Step-by-step explanation:

Step 1: Define

Identify given.

$\displaystyle \int {e^{5x}} \, dx$

Step 2: Integrate Pt. 1

Identify variables for u-substitution.

Set u:
$\displaystyle u = 5x$
[u] Differentiate [Derivative Rules and Properties]:
$\displaystyle du = 5 \ dx$

Step 3: Integrate Pt. 2

[Integral] Rewrite [Integration Property - Multiplied Constant]:
$\displaystyle \begin{aligned}\int {e^{5x}} \, dx & = \frac{1}{5} \int {5e^{5x}} \, dx \\\end{aligned}$
[Integral] Apply Integration Method [U-Substitution]:
$\displaystyle \begin{aligned}\int {e^{5x}} \, dx & = \frac{1}{5} \int {5e^{5x}} \, dx \\& = \frac{1}{5} \int {e^u} \, du \\\end{aligned}$
[Integral] Apply Exponential Integration:
$\displaystyle \begin{aligned}\int {e^{5x}} \, dx & = \frac{1}{5} \int {5e^{5x}} \, dx \\& = \frac{1}{5} \int {e^u} \, du \\& = \frac{e^u}{5} + C \\\end{aligned}$
[u] Back-substitute:
$\displaystyle \begin{aligned}\int {e^{5x}} \, dx & = \frac{1}{5} \int {5e^{5x}} \, dx \\& = \frac{1}{5} \int {e^u} \, du \\& = \frac{e^u}{5} + C \\& = \boxed{ \frac{e^{5x}}{5} + C } \\\end{aligned}$