Chapter 7: Problem 23
In Problems \(23-28,\) use the discriminant to identify the conic without actually graphing. $$ x^{2}-3 x y+y^{2}=5 $$
Short Answer
Expert verified
The conic is a hyperbola.
Step by step solution
01
Identify the general form of the conic
The given equation is already in the general form of a conic section: \[ Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0 \]For the equation \( x^2 - 3xy + y^2 = 5 \), the coefficients are \( A = 1 \), \( B = -3 \), and \( C = 1 \).
02
Calculate the discriminant
The discriminant of a conic section given by the equation \( Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0 \) is calculated as:\[ D = B^2 - 4AC \]Substitute \( A = 1 \), \( B = -3 \), and \( C = 1 \) into the discriminant formula:\[ D = (-3)^2 - 4(1)(1) = 9 - 4 = 5 \]
03
Identify the type of conic based on the discriminant
To identify the type of conic section:- If \( D > 0 \), the conic is a hyperbola.- If \( D = 0 \), the conic is a parabola.- If \( D < 0 \), the conic is an ellipse.Here, \( D = 5 > 0 \), indicating the conic is a hyperbola.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Discriminant
The discriminant is a crucial mathematical tool that helps us determine the nature of conic sections without graphing them. For equations in the form \( Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0 \), the discriminant \( D \) is calculated using the formula:
- \( D = B^2 - 4AC \)
- If \( D > 0 \), the conic section is a hyperbola.
- If \( D = 0 \), the conic section is a parabola.
- If \( D < 0 \), the conic section is an ellipse.
Hyperbola
A hyperbola is a type of conic section represented by an equation where the discriminant \( D > 0 \). This means hyperbolas happen when the curve is more stretched compared to ellipses or circles.Hyperbolas can be visualized as twin curves that mirror each other across a central point, and they tend to curve outwards. They appear in many different contexts, from architecture to physics.The simplest form of a hyperbola is given by \( rac{x^2}{a^2} - rac{y^2}{b^2} = 1 \) or its rotated version. Whenever you encounter a conic section with \( D > 0 \), it is safe to classify the shape as a hyperbola.
General Form of a Conic
The general form of a conic section provides a standardized way of expressing conic equations, which is:
- \( Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0 \)
Conic Section Classification
Conic section classification is a method to differentiate between the types of curves formed in a plane by intersecting a cone with a plane. The classification is mainly based on the value of the discriminant in the general conic equation.Different types of conic sections include:
- Circle: A special case of an ellipse when \( A = C \) and \( B = 0 \).
- Ellipse: Formed when \( D < 0 \) with \( A eq C \).
- Parabola: Occurs when \( D = 0 \).
- Hyperbola: The curve when \( D > 0 \), indicating two open, diverging paths.