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AP Calculus BC
Unit 7: Differential Equations
7.2 Verifying Solutions for Differential Equations
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Cards (21)
A solution to a differential equation is a
function
A solution to a differential equation must make the equation true when
substituted
The arbitrary constant in the solution y = x^{2} + C</latex> is represented by the letter
C
The derivative of
x
2
+
x^{2} +
x
2
+
C
C
C
is
2
x
2x
2
x
Substituting a function into a differential equation helps verify if the function is a
solution
One step in substituting a function into a differential equation is to find its
derivatives
Steps to substitute a function into a differential equation:
1️⃣ Find derivatives
2️⃣ Substitute into the equation
3️⃣ Simplify the equation
Simplifying the equation after substitution helps confirm if the function is a
solution
Combining like terms is a step in simplifying the
equation
What is a solution to a differential equation?
A function that makes it true
Substituting a function into a differential equation helps verify if the function is a
solution
Steps to substitute a function into a differential equation
1️⃣ Find derivatives
2️⃣ Substitute into the equation
3️⃣ Simplify
The function
y
=
y =
y
=
e
−
2
x
e^{ - 2x}
e
−
2
x
is a solution to
d
y
d
x
+
\frac{dy}{dx} +
d
x
d
y
+
2
y
=
2y =
2
y
=
0
0
0
What is the first step in simplifying an equation after substitution?
Combine like terms
Combining like terms is a key step in simplifying a differential equation after
substitution
To check if an equation holds true after simplifying, compare both
sides
Steps to check if an equation holds true
1️⃣ Simplify the equation
2️⃣ Compare both sides
3️⃣ Conclude if equation holds true
What is the primary goal of verifying a solution to a differential equation?
To check if it holds true
For exponential differential equations, simplification often involves using exponential
identities
The function
y
=
y =
y
=
C
e
−
3
x
Ce^{ - 3x}
C
e
−
3
x
is a solution to
d
y
d
x
+
\frac{dy}{dx} +
d
x
d
y
+
3
y
=
3y =
3
y
=
0
0
0
Match the differential equation type with its verification process
Linear ↔️ Substitute and simplify
Exponential ↔️ Use exponential identities