First Order Differential Equations

Description: This quiz covers the fundamental concepts and techniques related to First Order Differential Equations. It aims to assess your understanding of various methods for solving these equations, including exact equations, integrating factors, and separation of variables.
Number of Questions: 15
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Tags: first order differential equations exact equations integrating factors separation of variables
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Consider the differential equation $\frac{dy}{dx} + y = x$. Which of the following is the integrating factor for this equation?

  1. $e^{-x}$

  2. $e^x$

  3. $x$

  4. $1$


Correct Option: B
Explanation:

The integrating factor for the given equation is $e^x$ because it makes the equation exact.

Solve the following exact equation: $\left(2x + 3y\right)dx + \left(3x - 2y\right)dy = 0$.

  1. $x^2 + 3xy - y^2 = C$

  2. $x^2 - 3xy + y^2 = C$

  3. $2x^2 + 3xy - 2y^2 = C$

  4. $2x^2 - 3xy + 2y^2 = C$


Correct Option: A
Explanation:

To solve the exact equation, integrate each term with respect to its respective variable and combine the results.

Which of the following is a first order linear differential equation?

  1. $y' + y = x^2$

  2. $y'' + 2y' + y = 0$

  3. $y' = x^2 + y^2$

  4. $y''' - 3y'' + 2y' - y = 0$


Correct Option: A
Explanation:

A first order linear differential equation is one in which the dependent variable and its derivatives appear linearly.

Use the method of separation of variables to solve the following differential equation: $\frac{dy}{dx} = \frac{x}{y}$.

  1. $y^2 = x^2 + C$

  2. $y = x^2 + C$

  3. $y = \ln(x) + C$

  4. $y = x + C$


Correct Option: A
Explanation:

Separate the variables and integrate both sides to obtain the general solution.

Consider the differential equation $\frac{dy}{dx} = \frac{y}{x} + \frac{x}{y}$. Which of the following is a suitable substitution to solve this equation?

  1. $y = vx$

  2. $y = x^v$

  3. $y = \ln(x)$

  4. $y = e^x$


Correct Option: A
Explanation:

Substituting $y = vx$ transforms the equation into a separable equation.

Find the general solution of the differential equation $\frac{dy}{dx} = \frac{2x + y}{x}$.

  1. $y = x^2 + C$

  2. $y = x + C$

  3. $y = \ln(x) + C$

  4. $y = \frac{1}{x} + C$


Correct Option: A
Explanation:

This equation is a linear first order differential equation. Solve it using the integrating factor method.

Which of the following is a homogeneous first order differential equation?

  1. $y' + y = x$

  2. $y' = xy$

  3. $y'' + 2y' + y = 0$

  4. $y' = \frac{y}{x}$


Correct Option: D
Explanation:

A homogeneous first order differential equation is one in which the dependent variable and its derivatives appear only in terms of the independent variable.

Solve the following homogeneous differential equation: $\frac{dy}{dx} = \frac{y - x}{y + x}$.

  1. $y = x + C$

  2. $y = x^2 + C$

  3. $y = \ln(x) + C$

  4. $y = \frac{1}{x} + C$


Correct Option: A
Explanation:

This equation is a homogeneous first order differential equation. Solve it by substituting $y = vx$.

Consider the differential equation $\frac{dy}{dx} = \frac{x^2 + y^2}{xy}$. Which of the following is a suitable substitution to solve this equation?

  1. $y = vx$

  2. $y = x^v$

  3. $y = \ln(x)$

  4. $y = e^x$


Correct Option: A
Explanation:

Substituting $y = vx$ transforms the equation into a separable equation.

Find the general solution of the differential equation $\frac{dy}{dx} = \frac{2x + 3y}{x + 2y}$.

  1. $y = x + C$

  2. $y = x^2 + C$

  3. $y = \ln(x) + C$

  4. $y = \frac{1}{x} + C$


Correct Option: A
Explanation:

This equation is a linear first order differential equation. Solve it using the integrating factor method.

Which of the following is a Bernoulli differential equation?

  1. $y' + y = x$

  2. $y' = xy$

  3. $y'' + 2y' + y = 0$

  4. $y' = \frac{y}{x} + \frac{x}{y}$


Correct Option:
Explanation:

A Bernoulli differential equation is one in which the dependent variable and its derivatives appear in a product with the independent variable.

Solve the following Bernoulli differential equation: $\frac{dy}{dx} = x^2y - y^2$.

  1. $y = \frac{1}{x} + C$

  2. $y = \frac{1}{x^2} + C$

  3. $y = \ln(x) + C$

  4. $y = \frac{1}{x^3} + C$


Correct Option: A
Explanation:

This equation is a Bernoulli differential equation. Solve it by substituting $y = \frac{1}{v}$.

Consider the differential equation $\frac{dy}{dx} = \frac{y^2 + x^2}{xy}$. Which of the following is a suitable substitution to solve this equation?

  1. $y = vx$

  2. $y = x^v$

  3. $y = \ln(x)$

  4. $y = e^x$


Correct Option: A
Explanation:

Substituting $y = vx$ transforms the equation into a separable equation.

Find the general solution of the differential equation $\frac{dy}{dx} = \frac{x + y}{x - y}$.

  1. $y = x + C$

  2. $y = x^2 + C$

  3. $y = \ln(x) + C$

  4. $y = \frac{1}{x} + C$


Correct Option: A
Explanation:

This equation is a linear first order differential equation. Solve it using the integrating factor method.

Which of the following is a Riccati differential equation?

  1. $y' + y = x$

  2. $y' = xy$

  3. $y'' + 2y' + y = 0$

  4. $y' = \frac{y}{x} + \frac{x}{y}$


Correct Option:
Explanation:

A Riccati differential equation is one in which the dependent variable and its derivatives appear in a quadratic term.

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