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Ch. 2 - Functions and Graphs
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
Chapter 3, Problem 21

Write an equation in slope-intercept form of a linear function f whose graph satisfies the given conditions. The graph of ƒ passes through (−6, 4) and is perpendicular to the line that has an x intercept of 2 and a y-intercept of -4.

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1
Identify the slope of the given line using its intercepts. The line passes through the points (2, 0) and (0, -4). Use the slope formula: \(m = \frac{y_2 - y_1}{x_2 - x_1}\).
Calculate the slope of the given line by substituting the points: \(m = \frac{0 - (-4)}{2 - 0} = \frac{4}{2}\).
Determine the slope of the line perpendicular to the given line. Recall that perpendicular slopes are negative reciprocals, so if the original slope is \(m\), the perpendicular slope is \(-\frac{1}{m}\).
Use the point-slope form of a line equation with the perpendicular slope and the given point \((-6, 4)\): \(y - y_1 = m(x - x_1)\).
Rewrite the equation from the previous step into slope-intercept form \(y = mx + b\) by solving for \(y\) and simplifying.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Slope-Intercept Form of a Linear Equation

The slope-intercept form is y = mx + b, where m represents the slope and b is the y-intercept. This form makes it easy to identify the slope and where the line crosses the y-axis, which is essential for graphing and writing linear equations.
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Finding the Slope from Intercepts

A line's slope can be found using two points, such as the x- and y-intercepts. The slope m is calculated as the change in y divided by the change in x (m = (y2 - y1) / (x2 - x1)). Knowing the slope of the given line is necessary to find the slope of the perpendicular line.
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Perpendicular Lines and Their Slopes

Two lines are perpendicular if their slopes are negative reciprocals, meaning m1 * m2 = -1. If one line has slope m, the perpendicular line's slope is -1/m. This relationship helps determine the slope of the required line passing through a given point.
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