Chapter 12: Problem 7
Find the parametric equations that correspond to the given vector equation. $$ \mathbf{r}=3 t^{2} \mathbf{i}-2 \mathbf{j} $$
Short Answer
Expert verified
The parametric equations are \( x(t) = 3t^2 \) and \( y(t) = -2 \).
Step by step solution
01
Identify the Components
The given vector equation is \( \mathbf{r} = 3t^2 \mathbf{i} - 2 \mathbf{j} \). This vector is comprised of two components: one along the \( \mathbf{i} \) direction (the x-component) and one along the \( \mathbf{j} \) direction (the y-component).
02
Extract the X-Component
The x-component of the vector equation is the term associated with \( \mathbf{i} \). From the given equation \( \mathbf{r} = 3t^2 \mathbf{i} - 2 \mathbf{j} \), the x-component is \( x = 3t^2 \).
03
Extract the Y-Component
The y-component of the vector equation is the term associated with \( \mathbf{j} \). From the equation \( \mathbf{r} = 3t^2 \mathbf{i} - 2 \mathbf{j} \), the y-component is \( y = -2 \).
04
Write the Parametric Equations
Using the components extracted in the previous steps, we can write the parametric equations as: \( x = 3t^2 \) for the x-direction and \( y = -2 \) for the y-direction. Therefore, the parametric equations are: \[ x(t) = 3t^2, \, y(t) = -2 \].
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vector Equations
In mathematics, a vector equation describes a line or a curve in space by tracing points using a vector expression. A vector equation typically represents the position of a point as a function of a parameter, often denoted by \( t \). It consists of different components, each affecting a directional vector. In our example, the vector equation is given as \( \mathbf{r} = 3t^2 \mathbf{i} - 2 \mathbf{j} \).
- The term \( 3t^2 \mathbf{i} \) pertains to movement in the x-direction.
- The term \( -2 \mathbf{j} \) indicates movement in the y-direction.
X-Component
The x-component of a vector equation tells us how far along the x-axis the points on the line or curve are for any particular value of the parameter. For the vector equation \( \mathbf{r} = 3t^2 \mathbf{i} - 2 \mathbf{j} \), the x-component is extracted by isolating the part associated with \( \mathbf{i} \).
Here, the term is \( 3t^2 \mathbf{i} \), leading to the x-component as \( x = 3t^2 \). This expression means that the x-coordinate of a point on our line changes as the square of the parameter \( t \). It shows us that as the value of \( t \) varies, the line moves horizontally in a parabolic manner dictated by the function \( 3t^2 \).
Here, the term is \( 3t^2 \mathbf{i} \), leading to the x-component as \( x = 3t^2 \). This expression means that the x-coordinate of a point on our line changes as the square of the parameter \( t \). It shows us that as the value of \( t \) varies, the line moves horizontally in a parabolic manner dictated by the function \( 3t^2 \).
Y-Component
Just as the x-component provides horizontal information, the y-component offers a vertical description of our point's movement. Looking again at our vector equation \( \mathbf{r} = 3t^2 \mathbf{i} - 2 \mathbf{j} \), the component linked to \( \mathbf{j} \) is \( -2 \mathbf{j} \). From this, we can see that the y-component is simply \( y = -2 \).
Unlike the x-component, the value of \( y \) is constant here, meaning no matter what \( t \) is, the y-coordinate remains fixed at \( -2 \). This effectively makes our line or curve reside along a constant vertical level or y-value, translating into a horizontal line in parameter space.
Unlike the x-component, the value of \( y \) is constant here, meaning no matter what \( t \) is, the y-coordinate remains fixed at \( -2 \). This effectively makes our line or curve reside along a constant vertical level or y-value, translating into a horizontal line in parameter space.
Parametrization
Parametrization is the process of selecting a parameter to describe a curve or surface mathematically. It allows us to write equations that map a range of values into coordinates. In this example, the parametric equations that arise from our vector equation are essentially splitting the vector into two separate equations based on its components.
- The x-direction equation becomes \( x(t) = 3t^2 \).
- The y-direction equation is \( y(t) = -2 \).