Chapter 5: Problem 19
In Problems 19-22, evaluate \(\int_{C} y d x+x d y\) on the given curve from \((0,0)\) to \((1,1)\). $$ y=x^{2} $$
Short Answer
Expert verified
The line integral evaluates to 1.
Step by step solution
01
Understand the Problem
We need to evaluate the line integral \( \int_{C} y \, dx + x \, dy \) over the curve \( C \) which is given as \( y = x^2 \) from \((0,0)\) to \((1,1)\). This curve is a parabola.
02
Parameterize the Curve
The curve \( y = x^2 \) can be parameterized as \( x = t \) and \( y = t^2 \) for \( t \) ranging from 0 to 1. This means \( dx = dt \) and \( dy = 2t \, dt \).
03
Substitute into the Integral
Substitute the parameterization into the integral: \[ \int_{0}^{1} (t^2 \, dt + t \, (2t \, dt)) \]This simplifies to:\[ \int_{0}^{1} (t^2 + 2t^2) \, dt = \int_{0}^{1} 3t^2 \, dt \]
04
Evaluate the Integral
Evaluate the integral \( \int_{0}^{1} 3t^2 \, dt \). First, compute the antiderivative:\[ \int 3t^2 \, dt = t^3 + C \]Then, evaluate from 0 to 1:\[ \left[ t^3 \right]_{0}^{1} = (1)^3 - (0)^3 = 1\]
05
Conclude the Solution
The integral evaluates to 1, thus the value of the line integral over the given curve from \((0,0)\) to \((1,1)\) is 1.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Parabola
A parabola is a symmetrical, U-shaped curve that can open either upwards or downwards on a graph. The equation of a parabola in its simplest form is given by \( y = ax^2 + bx + c \). In our problem, the parabola is described by the equation \( y = x^2 \), which means our parabola opens upwards, starting from the origin point \((0,0)\).
- It has a vertex, which is the lowest point for an upward-opening parabola.- The vertex of the parabola \( y = x^2 \) is at \( (0, 0) \).- A parabola is symmetric along its vertical line of symmetry, which, for \( y = x^2 \), is the y-axis.
Understanding parabolas helps in recognizing the curve shapes in graphical problems, which is crucial for calculating specific types of integrals like line integrals.
- It has a vertex, which is the lowest point for an upward-opening parabola.- The vertex of the parabola \( y = x^2 \) is at \( (0, 0) \).- A parabola is symmetric along its vertical line of symmetry, which, for \( y = x^2 \), is the y-axis.
Understanding parabolas helps in recognizing the curve shapes in graphical problems, which is crucial for calculating specific types of integrals like line integrals.
Parameterization
Parameterization is the process of expressing a curve using a single parameter, often denoted by \( t \). In line integrals, this helps by taking multi-dimensional curves and simplifying them into single-variable expressions.
For the equation \( y = x^2 \), to parameterize the curve, assign:
Parameterization helps simplify the integral by transforming derivatives into terms of \( dt \), such as \( dx = dt \) and \( dy = 2t \cdot dt \). This simplification is valuable for easily substituting into the integral for evaluation.
For the equation \( y = x^2 \), to parameterize the curve, assign:
- \( x = t \)
- \( y = t^2 \)
Parameterization helps simplify the integral by transforming derivatives into terms of \( dt \), such as \( dx = dt \) and \( dy = 2t \cdot dt \). This simplification is valuable for easily substituting into the integral for evaluation.
Antiderivative
Finding the antiderivative, also known as the indefinite integral, is a fundamental part of solving integrals. It involves determining a function whose derivative is the given function.
In the problem, after substituting the parameterized expressions into the integral, you need to find the antiderivative of \( 3t^2 \). The antiderivative of \( 3t^2 \) is found using the power rule:\[ \int 3t^2 \, dt = t^3 + C\]
Here, \( C \) is the constant of integration, which we typically set aside in definite integrals as we evaluate over a specific interval.
Knowing how to find antiderivatives allows you to handle a variety of integrals, which is an essential skill in calculus.
In the problem, after substituting the parameterized expressions into the integral, you need to find the antiderivative of \( 3t^2 \). The antiderivative of \( 3t^2 \) is found using the power rule:\[ \int 3t^2 \, dt = t^3 + C\]
Here, \( C \) is the constant of integration, which we typically set aside in definite integrals as we evaluate over a specific interval.
Knowing how to find antiderivatives allows you to handle a variety of integrals, which is an essential skill in calculus.
Integral Evaluation
Integral evaluation is the process of computing the value of definite integrals over a specified interval. This involves using the antiderivative to find values at boundary points and subtracting them.
For our problem, compute the definite integral:\[ \int_{0}^{1} 3t^2 \, dt\]Using the antiderivative \( t^3 \), evaluate from \( 0 \) to \( 1 \):\[ \left[ t^3 \right]_{0}^{1} = (1)^3 - (0)^3 = 1\]
The computed value, \( 1 \), gives the result of the line integral over the curve \( y = x^2 \) from \((0,0)\) to \((1,1)\). Integral evaluation is crucial for determining the total "weight" or "sum" of a function over a path or area.
For our problem, compute the definite integral:\[ \int_{0}^{1} 3t^2 \, dt\]Using the antiderivative \( t^3 \), evaluate from \( 0 \) to \( 1 \):\[ \left[ t^3 \right]_{0}^{1} = (1)^3 - (0)^3 = 1\]
The computed value, \( 1 \), gives the result of the line integral over the curve \( y = x^2 \) from \((0,0)\) to \((1,1)\). Integral evaluation is crucial for determining the total "weight" or "sum" of a function over a path or area.