Answer:
Part A: [tex]\displaystyle f(x) = \frac{19}{2}x^2 + 15x + C[/tex]
Part B: [tex]\displaystyle f(x) = \frac{19}{2}x^2 + 15x - 5[/tex]
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Equality Properties
- Multiplication Property of Equality
- Division Property of Equality
- Addition Property of Equality
- Subtraction Property of Equality
Algebra I
Functions
Calculus
Differentiation
- Derivatives
- Derivative Notation
Differential Equations
Integration
- Integrals
- [Indefinite Integrals] Integration Constant C
Integration Rule [Reverse Power Rule]: [tex]\displaystyle \int {x^n} \, dx = \frac{x^{n + 1}}{n + 1} + C[/tex]
Integration Property [Multiplied Constant]: [tex]\displaystyle \int {cf(x)} \, dx = c \int {f(x)} \, dx[/tex]
Integration Property [Addition/Subtraction]: [tex]\displaystyle \int {[f(x) \pm g(x)]} \, dx = \int {f(x)} \, dx \pm \int {g(x)} \, dx[/tex]
Step-by-step explanation:
Step 1: Define
Identify
[tex]\displaystyle f'(x) = 19x + 15[/tex]
Step 2: Find Antiderivative
- [Derivative] Integrate both sides: [tex]\displaystyle \int {f'(x)} \, dx = \int {19x + 15} \, dx[/tex]
- [Left Integral] Simplify: [tex]\displaystyle f(x) = \int {19x + 15} \, dx[/tex]
- [Integral] Rewrite [Integration Property - Addition/Subtraction]: [tex]\displaystyle f(x) = \int {19x} \, dx + \int {15} \, dx[/tex]
- [Integrals] Rewrite [Integration Property - Multiplied Constant]: [tex]\displaystyle f(x) = 19 \int {x} \, dx + 15 \int {} \, dx[/tex]
- [Integrals] Integration Rule [Reverse Power Rule]: [tex]\displaystyle f(x) = 19 \bigg( \frac{x^2}{2} \bigg) + 15x + C[/tex]
- Simplify: [tex]\displaystyle f(x) = \frac{19}{2}x^2 + 15x + C[/tex]
Step 3: Find Particular Solution
- Substitute in function value [Function f(x)]: [tex]\displaystyle 87 = \frac{19}{2}(-4)^2 + 15(-4) + C[/tex]
- Evaluate: [tex]\displaystyle 87 = 92 + C[/tex]
- Solve: [tex]\displaystyle C = -5[/tex]
- Substitute in C [General Solution]: [tex]\displaystyle f(x) = \frac{19}{2}x^2 + 15x - 5[/tex]
Topic: AP Calculus AB/BC (Calculus I/I + II)
Unit: Differential Equations