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Ch. 2 - Graphs and Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 3, Problem 64

Graph the line passing through the given point and having the indicated slope. Plot two points on the line. through (9/4 , 2), undefined slope

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1
Recognize that an undefined slope means the line is vertical. A vertical line has the form \(x = a\), where \(a\) is the x-coordinate of every point on the line.
Identify the x-coordinate of the given point, which is \(\frac{9}{4}\). Since the slope is undefined, the equation of the line is \(x = \frac{9}{4}\).
To graph the line, draw a vertical line passing through \(x = \frac{9}{4}\) on the coordinate plane. This line will go straight up and down through this x-value.
To plot two points on the line, choose any two different y-values (for example, \(y = 0\) and \(y = 1\)), and pair them with \(x = \frac{9}{4}\). So the points are \(\left(\frac{9}{4}, 0\right)\) and \(\left(\frac{9}{4}, 1\right)\).
Plot these two points on the graph and draw the vertical line through them to complete the graph of the line with undefined slope passing through \(\left(\frac{9}{4}, 2\right)\).

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Key Concepts

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

Undefined Slope

An undefined slope occurs when a line is vertical, meaning it goes straight up and down. This happens because the change in x (horizontal change) is zero, making the slope formula division by zero, which is undefined.
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Types of Slope

Equation of a Vertical Line

A vertical line passing through a point (x, y) has the equation x = constant, where the constant is the x-coordinate of the point. This means all points on the line share the same x-value.
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Standard Form of Line Equations

Plotting Points on a Vertical Line

To plot points on a vertical line, choose different y-values while keeping the x-value constant. For example, if the line passes through (9/4, 2), points like (9/4, 1) and (9/4, 3) lie on the line.
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Finding Equations of Lines Given Two Points