Chapter 3: Problem 22
(a) The equation \(x+y=1\) can be viewed as a linear system of one equation in two unknowns. Express a general solution of this equation as a particular solution plus a general solution of the associated homogeneous system. (b) Give a geometric interpretation of the result in part (a).
Short Answer
Expert verified
The general solution is \((x, y) = (1+t, -t)\) and geometrically, it's a line parallel to \(x+y=0\), passing through \((1,0)\).
Step by step solution
01
Understanding the Equation
The given equation is \( x+y = 1 \). This is a linear equation in two variables. We will consider it as a system of equations where only one equation is provided, involving two unknowns \( x \) and \( y \).
02
Solution to the Homogeneous Equation
The associated homogeneous equation is obtained by setting the right-hand side to zero, giving \( x + y = 0 \). This represents a line through the origin where \( y = -x \). The general solution is any point on this line: \((x, -x)\).
03
Find a Particular Solution
Choose specific values for \( x \) and \( y \) that satisfy the original equation \( x + y = 1 \). One simple choice is \( x = 1 \), \( y = 0 \), thus a particular solution is \((1, 0)\).
04
Formulate the General Solution
Combine the particular solution from Step 3 with the general solution of the homogeneous equation from Step 2. Thus, the general solution is \( (x, y) = (1, 0) + (t, -t) \), where \( t \) is a real number denoting parameter.
05
Express the General Solution
Express the derived solutions explicitly: \( x = 1+t \) and \( y = -t \). This represents the general solution for \( t \in \mathbb{R} \).
06
Geometric Interpretation
The original equation \( x+y = 1 \) represents a line in the plane, which is parallel to and one unit above the line \( x+y = 0 \). The general solution found represents every point on this line, shifting along the direction defined by the vector \((1, -1)\). Thus, the line is infinitely extended, defined by the particular point \((1,0)\) and shifted by \((t, -t)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
General Solution
In the context of linear equations, finding a general solution is a way to express every potential solution to the equation. For the equation \(x + y = 1\), the general solution combines two components: a particular solution and the solution to the associated homogeneous system.
- A particular solution is a specific set of values for \(x\) and \(y\) that satisfies the equation. For example, choosing \(x = 1\) and \(y = 0\) yields \(x + y = 1\), thus \((1, 0)\) is a particular solution.
- The general solution of the homogeneous equation derives from \(x + y = 0\), the equation formed by setting the right side of the original equation to zero. This homogeneous equation describes points lying along a line through the origin, specifically \((x, -x)\).
- By combining these, the general solution for \(x + y = 1\) becomes \((x, y) = (1, 0) + (t, -t)\), where \(t\) can be any real number.
Homogeneous System
A homogeneous system in terms of linear equations is a system where all constant terms are zero, such as \(x + y = 0\). Here, each solution of such a system forms a vector space, capturing infinite solutions through vectors.
In the specific case of \(x + y = 0\), this system indicates a line through the origin where \(y\) equals \(-x\), i.e., \((x, -x)\).
In the specific case of \(x + y = 0\), this system indicates a line through the origin where \(y\) equals \(-x\), i.e., \((x, -x)\).
- This line can be described using a parameter \(t\), whereby any point on the line can be denoted as \(\{(t, -t) \mid t \in \mathbb{R}\}\).
- The solutions form a vector, or a line, through the origin, which plays an essential role in forming a framework for solving non-homogeneous equations.
Geometric Interpretation
Linear equations can be beautifully visualized in geometric terms. Each equation represents a line in a coordinate space. For \(x + y = 1\), this equation represents a line plotted at exactly one unit above the origin line formed by \(x + y = 0\).
- The geometric interpretation reveals the nature of the line, how it traverses the plane, specifically parallel to the line represented by \(x + y = 0\).
- The general solution found \((x, y) = (1, 0) + (t, -t)\) corresponds to a line shifting along a direction vector \((1, -1)\). As \(t\) varies, different points along this line are reached, indicating the line's parallel expansion.
- The particular solution \((1, 0)\) serves as a specific point on this line, and variations introduced by \(t\) express movement along the plane, respecting the linearity and directionality inherent in the equation.