/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 5 Find the equation of a line thro... [FREE SOLUTION] | 91Ó°ÊÓ

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Find the equation of a line through (2,-3) that is parallel to the line with equation \(r=3 i-7 j+\lambda(4 i-3 j)\).

Short Answer

Expert verified
The equation of the line is \(y = -\frac{3}{4}x - \frac{3}{2}\).

Step by step solution

01

Understand the Given Line

The given line is expressed in vector form, with equation \( \mathbf{r} = 3\mathbf{i} - 7\mathbf{j} + \lambda(4\mathbf{i} - 3\mathbf{j}) \). This represents a line through the point \((3, -7)\) and in the direction of \((4, -3)\).
02

Identify the Slope of the Given Line

The direction vector of the line is \((4, -3)\). The slope of a line having the direction vector \((a, b)\) is \( \frac{b}{a} \). Therefore, the slope of this line is \(-\frac{3}{4}\).
03

Use the Slope for the Parallel Line

Lines that are parallel have the same slope. Hence, the slope of the line through \((2, -3)\) that is parallel to the given line is also \(-\frac{3}{4}\).
04

Apply the Point-Slope Form

The point-slope form of a line's equation is \(y - y_1 = m(x - x_1)\). Here, \((x_1, y_1) = (2, -3)\) and the slope \(m = -\frac{3}{4}\). Substitute these values to get: \[y + 3 = -\frac{3}{4}(x - 2)\].
05

Simplify to Find the Line's Equation

Expand and simplify the equation: \[y + 3 = -\frac{3}{4}x + \frac{3}{2}\]. Subtract 3 from both sides to get: \[y = -\frac{3}{4}x + \frac{3}{2} - 3\]. Further simplification gives: \[y = -\frac{3}{4}x - \frac{3}{2}\].

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Vector Equations
Vector equations are a way to represent lines in a more geometric form. A vector equation of a line typically includes a starting point vector and a direction vector. For instance, in the problem at hand, the line is given as \( \mathbf{r} = 3\mathbf{i} - 7\mathbf{j} + \lambda(4\mathbf{i} - 3\mathbf{j}) \). This is interpreted as:
  • \( 3\mathbf{i} - 7\mathbf{j} \), the point from which the line passes.
  • \( \lambda(4\mathbf{i} - 3\mathbf{j}) \), a direction vector scaled by a parameter \( \lambda \).
The direction vector tells us the line's trajectory in relation to the coordinate axes. When asked for a parallel line, this direction vector plays a crucial role since the parallel line will have the same direction vector. Vector equations are instrumental due to their compact representation and ease of use in calculations.
Slope-Intercept Form
The slope-intercept form is a popular way to express the equation of a line. It is represented as \( y = mx + b \), where \( m \) is the slope and \( b \) is the y-intercept. This form is straightforward because it openly tells us:
  • How steep the line is through its slope \( m \).
  • Where the line crosses the y-axis, indicated by \( b \).
For our given problem, converting the simplified equation \( y = -\frac{3}{4}x - \frac{3}{2} \) into the slope-intercept form shows that the slope \( m \) is \( -\frac{3}{4} \) and the y-intercept \( b \) is \( -\frac{3}{2} \).
Knowing the slope makes understanding the line's behavior intuitive. Negative slopes imply that as \( x \) increases, \( y \) decreases, which visually tilts the line downwards from left to right.
Point-Slope Form
The point-slope form is particularly effective for writing equations of lines when you're given a point and a slope. It is expressed as \( y - y_1 = m(x - x_1) \). Here, \((x_1, y_1)\) is a known point on the line, and \( m \) is the slope. This form is advantageous because:
  • It's easy to construct using a specific point and slope.
  • It helps transition to other forms, like the slope-intercept form, by simplification.
For the exercise, using the point \((2, -3)\) and slope \( -\frac{3}{4} \), the initial equation is set up. By applying the point-slope form, we get:\[ y + 3 = -\frac{3}{4}(x - 2) \]This equation can then be transformed into either vector or slope-intercept forms by further simplification, enhancing its versatility for solving and analyzing the problem.

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